There's another discussion going on this forum now about a Chevy 216 in a GMC. Your biggest problem will be the front motor mount but many have made a plate adapter. Then modify exhaust and throttle linkage as necessary...
Useful info here
http://www.patricksantiquecars.com/articles.html scroll about halfway down.
Wonder why the existing engine has low/no compression. It could be a big problem or maybe not so big.
Good luck with it.
