700R4/4L60(e) wont hold the power, i dont care what anyone tells you...ive asked around many shops, even the good reputable builders dont want to warranty over 450 to the wheels or so.

200R4 would be the better bet, the GN/TTA guys are doing 9's with them all day, but they are very built, the th350 and 400 are my choice trannies, id go with the 400 cause it can be made a bit beefier, but you lose a little more power through the drive train.

last resort, 4L80E...but that seems liek a tough one to fab.