Fullthrottledan1

If i were to go from 853 casting ls1 heads to 317 casting truck heads how much of a difference would that make? reason im asking is because i have the 853's on my 370 right now, .040 gaskets, and im hitting a piston with an intake valve. cam is only .551 lift. static compression is 9.1:1 now, so im sure ill lose some by going to the 317s. any help would be appreciated
Dan