Cool idea for vintage cars that were unremarkable when it came to driving characteristics or where only the frame and/or body survived with no drivetrain and hard to source donors.
In fact, there are still complete, servicable engines _and chassis_ available. And the chassis are already registered with a VIN, so when built can be sold as a new 1984 model year vehicle.
Yeah, I thought of the first corvettes that had catalytic converters:
1974 models had the last true dual exhaust system that was dropped on the 1975 models with the introduction of catalytic converters requiring the use of no-lead fuel. Engine power decreased with the base ZQ3 engine producing 165 hp (123 kW; 167 PS), the optional L82's output 205 hp (153 kW; 208 PS), while the 454 big-block engine was discontinued.