That 315+ is way way more than I've gotten out of them. But, I'm usually going for the no-holes-no-tubes plan. I think low 280's is the best I've gotten out of a basic porting job, 2.055 valve. Those made 589hp on a 419.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
