If this car had a Pontiac 400 engine, who knows? Those cars never came with a Pontiac engine until the '74 GTO version, and even then, it was a 350. Now when you're trying to put a SBC back in, who's to say? The biggest engine that car came with was a 307 SBC. That car has had 34 years to be cobbled. Who's to say it needs the Z-bar? My guess is that car came with a six cylinder and an automatic to start with.