I was going to go LSx, but I don't think I can pass up $2,000ish swapped for a v8 (even though 256whp is a little low)
Also thought you guys might want to check this out.
Bullet Cars - Supercharger Kits Toyota 1UZFE
Bullet supercharged of Australia, offers a m90 supercharger kit ($300-600 used s/c) that would be good to add another 170 or so hp. What are you guys using for engine management for your stuff?