Off hand, the Can Am block should have a larger bore (sleeve) size -- 4.440-inches versus 4.25-inches for the ZL1. The original Can Am engine was built with a short stroke (3.47...I think, but I'm getting old) for a final displacement of 430 cubic inches, but that changed quickly.....a 4.0-inch 454 crank produced a 494. And as we all know, there's "no replacement for displacement" <g>. IIRC there are other differences, but that's the big one.

Wayne