A while ago I was looking around for parts like you'd probably be interested in so I'll state what may be obvious: you can probaby find some of the parts used for good prices, especially parts like intake manifolds and heads.

There are plenty of articles comparing results of upgraded SBC's but this one by Hot Rod magazine working on a ZZ4 will give you some good general ideas about what kind of parts seem to work: Small-Block Chevy Bolt-Ons - We Add 117HP To The ZZ4 Crate Engine - Hot Rod Magazine