i have put big blocks with the pistons out of the deck 0.10 but not that much .this is to much for me . and if it has a lot of piston to wall clearances the piston will rock and boy you are getting close if you know some one with a mill? so you can trim this part of the piston down 0.25 this is not a big deal . do not grab the pistons by the skirt when cutting the tops so you do not hurt the pistons when done sand the pistons smooth take all shape edges off tops when done the pistons should feel like a old bar of soap i sand them to 400 sand paper. the little scotch brite discs work good as fare as the compression i would cc the head you can buy one hell of a buret on the net and moroso makes a side card that will help you on the compression . it dos not take much piston dome on this with a 4 1/2 stroke and a 4.375 bore it will sneak up fast