well to be exact i put an indicator on the piston and checked from the top of the deck and the flat part of the top of the piston pro trueds .025 abovethe deck height. but the piston has about a 1/8'' dome on it, the heads are off of a 90's 454,not for sure the chamber cc,and also not for sure how to figure the comp. ratio off of this info.,the pistons are supposed to be 10:1's. and i agree about the 4.370 head gaskets having a slight over lap into the cylinder. and was the part # that you gave pat the one for the 4.375 bore?OH! by the way i'm enjoying this and i really appreciate all the info and input on this project from all the angles that it is being looked at. thanks again and i hope ya'll keep it rolling in because i'm considering all things on this motor. wjr.