For a budget, and future use on a 360, I'd recommend Magnum heads. Yep, lots of JY ones are cracked, but they'll be cracked on wrecked vehicles, and they don't crack from sitting. They'll be fine. If you want to drop $700 now, get Enginequest or Hughes Iron Rams, they are new/improved non-cracking Magnums with better ports.

Search for Magnum builds and posts by Patrick and Scratchinfotraction. They always have good info.