The previous owner of our car had a 493 with 286 heads and a Bullet 313/321 roller cam that made 614 HP using a stock cross ram and Edelbrock 750 AFBs. I'm guessing compression was about 12-1. The manifold will be the limiting factor as it is sized to flow 426 cu-in. We picked up 3 tenths going to a 440-25 intake. Car ran a best of 10.30's with the stock cross ram and 440-1 heads.