i have a 400 30 over trw flat tops xe 284 comp cam 72 cc heads with 995 valve springs 10 degree retainers heads ported all the way through performer rpm intake 750 mighty demon carb msd ign.heddman 1 3/4 headers through 3 in.ex i'm going to put heads cam intake carb ign.headers on 455 30 over with trw flat tops(not concern with compression)i was wondering what kind of gain i would see and any suggestion thanks