would twin T04 turbos (58mm) i believe be able to make 1000 horse power. they say they are cable up to 650 a piece. the other choice would be the 67's or maybe just 1 big 88 or something. let me know what you thing oh and check out these log tubes

http://www.jgstools.com/turbo/thk.html

looks interesting i could put the T04's on their.

 

Twin 58s should be able to make 1000 rwhp. The Stenod Formula is running a pair of GT40s (59mm) and just ran 8.99 over the weekend. Maybe they can tell you what their dyno numbers are.

That manifold is kind of cool/simple, but I don't see any LS1 applications.