I don't think the 700R is a great transmission, it is popular though. Plent of folks building these trannys and you will need at least a level 2 build for your HP #'s. Here's a couple of links both are for trannys up to 500HP and around 450 FTlbs of torque.

http://racetransmissions.com/store/p...products_id/32

http://www.transmissioncenter.net/hi...0r4.htm#Stage2

good Luck RS