I was looking for a virgin 4-bolt block, those are hard to find.

Corvette, what do you want to do? How involved do you want to get? I wanted to build a 9.5:1 compression motor that ran on 87 octane and made close to 300 hp. I couldn't find any shortblocks that would do that so I built my own. If you want to make 350-400 hp, the ZZ4 crate motor is hard to beat. If you have most of hte parts and want to save some money, GM makes a ZZ4 short block (roller cam ready).