When it comes to piston to head clearances you need to check the deck hieght on both sides(cam side and outside of the block ) of the pistons, all 8 of them. Bring the piston up until it is at the end of its upwards travel and then use a thin bladed screwdriver or what ever you want to use, to get between the edge of the pistons on the cam side and the block and rock the piston towards the opposite side, read, measure, the deck hieght write it down Then do the other side of the piston and write that down I have found that I needed more than .035 and less than .041 piston to head clearance to have no marks on either of them after running for awhile at the track and on the street Good luck