I have to agree with the first post, leave the block stock and don't touch the bottom end. They are known to handle 500+ hp with no issues, and it will save you some money aswell. If the engine blows up its either user error or a part failure that could happen at anytime.

Sounds like this whol build can be done for under $10,000 if most of the work is done yourself, the biggest things are the transmission, rims/tires, paint and interior.