Right now I am going to run the 400 as it is unless I have to change anything. Yes it is 0.020 over making the bore 4.145(lol, kinda wierd I measured it a few times to make sure I didn't screw it up). The pistons seem to be flat tops with 4 valve reliefs, they have a part number on the I'll try to find out who made them tommorrow. They look like exactly like the pistons I pulled out of one of my 350s except that they are hyperteurics(least i think they are, and sorry I think I spelled that wrong). So the 400 heads have 76cc combustion chamber right? And with the flattop pistons chevy was using at the time it made about 8.5:1 compression, wouldn't dropping the combustion chamber just raise the combustion up to about 9.5:1 or maybe 10:1? I'm not trying to argue or anything but this is how I was figuring the compression would end up or am i just missing something big? And thanks alot for the help techinspector1


I'll get the deck height for you tommorrow