There have been many European sports cars that have used large American engines. From my generation there was the Jensen Healey Interceptor and Bristol using Chrysler engines. The AC Cobra, and Sunbeam Tiger using Ford engines.
But here is a rare American/Italian sports car using a GM engine and suspension. I'm not fond of GM, but this car is good looking enough to keep company with any European exotic of the period. The styling is obviously inspired by Ferrari, but I think the result is unique enough.
At first the Apollo 3500GT used the new Buick 3.5 litre all aluminium V8. Light at 318lb, the car weighed just 2400lb (Later the copyright for this engine was sold to Rover who used it in the massive P5B, petite P6B, SD1 V8, and Landrover). And it has a 4-speed manual! The suspension and steering are from an early 1960's Buick Skylark. The rear live axle is located by four links and coil springs, so it might even handle well.
The aluminium body and interior were built in Turin, by Carrozzeria Intermeccanica. The body was mounted to the frame and then shipped to Oakland California where the drivetrain and suspension were installed.
Only 107 were built. That includes 76 Apollo coupes, 11 Apollo convertibles, a 2+2 prototype, and 19 Vetta Venturas built in Dallas, Texas. I'm guessing that it was those latter cars that used a larger and heavier 300cu.in. cast iron Buick V8 (Apollo 5000GT).
Photos from eBay
Thanks Bring a Trailer Intermeccanica Apollo/Vetta Ventura