Is the number you shoot for .040 with an open chamber iron head? What I got is a flat top piston and my farthest one down is .008 in the hole with a .028 head gasket an .011 on the flat of the head to the small flat area in the chamber of my small block J head. Oh and on the other side pistons are zero with the deck. I just had the shop clean the decks till they were flat is why the difference from on side to the next. The side that is zero now was high from one end to the other and accounts for why a little more was taken of the deck on that side. It was pretty flat just not true with the crank front to back when it left Mopar orignally back in 1967.