If the rotating assembly is all stock specs, then the pistons should be out of the hole a few thou, like .004" - .008" at TDC. This always varies between builds (even from the factory) and even seems to always vary between cylinders. Typically, the corner cylinders (numbers 1, 2, 7 and 8) will be more out of the hole than the center ones (numbers 3, 4, 5 and 6). Always measure your assembled one. You'll need a head gasket at least about .037" more than the highest piston, just to give you rough figures.