Generally, a newer, more high performance engine is installed into an older body. After 1971, performance went in the toilet. New motors make power now, but they have a bunch of plastic on them, and just don't look right to me in an older car. Generally, something like a '20s or '30s Ford should have a flathead V8. A smallblock Chevy is often used, too, but that just sux, in my opinion. It may be a lot faster, but who cares? It's not cool. A '50s or older Mopar is perfect for a 392 Hemi. That motor in a '60s car is going in the wrong direction since those cars were available with a 426 Hemi, and the 392 wasn't really a high performance engine, whereas the 426 was a race engine from it's inception.