What began as a daily driver quickly evolved into something more serious. Over the years Allen methodically modified the car, starting with a steeper 4.11 set of gears in place of the factory 3.36 units. The need for speed was very much at play and that led to the eventual installation of more aggressive 4.88 gears, headers, a camshaft upgrade, and a bigger Holley carburetor and intake. By the mid 1960s the Impala had transformed from a new-car purchase that was being street raced into a competitive race car—one that Allen would campaign successfully. “I ran A-class and become Ohio’s A-class champion,” he says.

As the 1960s wound down, so did Allen’s race activities with the Impala. In 1969 he parked the car, however, a few years later, around 1972, Allen’s son, Jeff, decided to take on the task of freshening the car and making sure it was once again mechanically sound. The goal was not to convert it back into a mild road car but to rebuild and maintain it in its race-ready configuration. The project’s initial goal was a full disassembly, with Jeff taking the car apart. As with many long-term automotive projects, within a matter of months the process stalled before it could be completed. Allen states, “I think life got in the way with family and a career.”

The hands of time moved forward a few decades, and Allen was finally ready to get the Impala back on the road. The search for a builder set off a series of shop moves. The first shop managed to set the body on a new Roadster Shop SPEC chassis and mock in a 409 engine, but before the project could progress further, the shop closed. The car was then moved to a second shop, where some bodywork issues were addressed, only for that shop to close as well after the owner died, leaving the Impala in limbo once again. Yet in 2017, Allen took a major step toward realizing his Z11 dream. “I went to the Mecum Auction in Kissimmee to bid on a set of Z11 aluminum fenders, hood, and front bumper from the Don Fezell collection,” he recalls. “I didn’t initially realize they also had a Z11 engine there and I managed to bid on it, but I missed a call and it was sold to somebody else. When the parts were delivered to my shop, I mentioned that I still wanted the engine. I was told, ‘You still can. The guy never picked it up.’”

The current chapter of the Impala’s story began when Allen decided to seek out someone new to finish what had been started. That’s where Derek Oberlander, owner of Oberlander Performance, entered the picture. Allen had first met him many years earlier while the car was at the first shop.

Once the Impala was dropped off and work began, Allen and Oberlander discussed exactly what he wanted and how he planned to use the car. Returning it to its race car roots was completely off the table; Allen was looking for a fully streetable car he could genuinely enjoy. Within that goal there was room for creativity and modernization, but one thing was non-negotiable. Oberlander recalls, “I tried to talk him into an LS engine dressed to look like a Z11, but he was adamant about using the original Z11 engine he had purchased. He did, however, allow me to modernize it with things like fuel injection.”

The prior purchase of the RS chassis significantly advanced the project by resolving many of the inefficiencies inherent in the original chassis and suspension. The car’s limited use after being designated race-only, combined with decades of hibernation, also helped preserve the sheet metal, which required only minor bodywork. While this was true of the original steel, the aluminum Z11 components were not as fortunate. As Oberlander explains, “The aluminum parts were pretty banged up. The passenger side had been corroded by battery acid years ago, so I had to reconstruct some of the mounting tabs, but most of the work involved addressing dings and dents. I also reshaped the rear of the aluminum hood to better match the contour of the wiper grille for an improved fit.” The auction did not include an aluminum rear bumper or the Z11 air cleaner assembly; both were later sourced from Jim Sullivan, who produces faithful reproductions of these rare components.

As the body came together, the drivetrain was simultaneously mocked up in place. Oberlander fabricated custom headers and an exhaust system, and during this phase the wheel selection was finalized, with Allen choosing Forgeline ZX3P wheels wrapped in Continental rubber. Once the car reached the metal-finish stage, it was disassembled and handed off to Charlie Minerovic, who, working from his home shop, carried the Impala through final bodywork and paint. Staying true to the car’s original character, Allen opted to retain the factory Saddle Tan Metallic, refinished using a PPG basecoat/clearcoat system.

The body was only one piece of the puzzle—the other was the 409. The key objective was to retain the engine while taming its rowdy nature for street use. Starting with the purchased unit, Oberlander conducted research and delivered it to Lamar Walden Automotive (LWA) in Doraville, Georgia. It proved to be an excellent foundation, featuring a very solid block and a clean set of heads. The plan called for a complete internal rebuild, which included an LWA-spec 4340 steel stroker crankshaft, connecting rods, an LWA222 custom-ground camshaft, and forged aluminum pistons. Together, these upgrades increased displacement to 482 ci. On the top end, the 409 Z11 cast-iron heads were fully rebuilt. Induction blends old and new technology. The GM Z11 two-piece dual-quad/dual-plane aluminum intake was paired with a set of Holley Terminator X Max 4150 four-barrel EFI units. To complete the driveability package, a TREMEC T56 Magnum six-speed transmission was installed.

The full propulsion overhaul took roughly a year to complete and successfully balanced the owner’s goal of incorporating authentic Z11 components with modern performance enhancements. Oberlander also handled the wiring integration and resolved several technical challenges, including reconfiguring the fuel-injection system to eliminate interference issues. Another notable modification was the custom-machined hardware he fabricated to mount the iBooster and hydraulic clutch system.

With the drivetrain mated to the body, reassembly began, ushering in the final major phase of the build. Attention then turned to the interior, which was refreshed to match the overall vision by blending classic style with modern refinement. The original dash and seats were retained but thoughtfully upgraded. The seats and door panels were upholstered in Buckskin leather, while the dash was fitted with a Dakota Digital RTX system complete with a tach pod. Additional components, including an Ididit steering column, a Billet Specialties steering wheel, a custom Hurst shifter, and a Vintage Air A/C system, further enhanced the cabin with subtle modern touches.

From the moment the Impala rolled into Oberlander’s shop to the day Allen drove it out, the build spanned roughly three years. Reflecting on the result, Allen says, “I’m totally satisfied with the way it came out. The only thing we’re going to do this spring is change the differential. I originally ordered a 3.55:1 final drive and it was incorrect. We will be installing a 3.90:1 unit.”

FENDERS: Original Z11 aluminum
HOOD: Original Z11 aluminum, Z11 light spring hood hinges
PAINT: PPG Saddle Tan Metallic basecoat/clearcoat
BODY AND PAINT: Charlie Minerovic (Streetsboro, OH)
GRILLE: GM restored original
BUMPERS: GM original aluminum Z11 front bumper, reproduction aluminum Z11 rear bumper by Jim Sullivan, polished and rechromed by Grafton Metal Finishing (Grafton, OH)
TAILLIGHTS: GM original with LED bulbs
Headlights: Dapper LED
CHROME TRIM: Reconditioned original