G.H. , In retrospect, the next pistons we get will probably be domed similar to the one you show with the hole in it. The ones that we are currently using don't have any squish area. Buick wasn't wrong on a lot of things in their 1939 design. We are currently holding the compression at 8.0/1 for obvious reasons. The crank and bearings looked pretty good, given the abuse we subjected them to in our rookie outing. Mostly because we are limiting our RPM to 5000. D.G.