Winston Cup teams for over 20 years now have a system that pumps water heated to operating temps through the water jackets of their blocks while they are final honed. They also have used torque plates bolted to the bell housing to hone the cylinders as well. We used a bell housing plate torqued to our H/MP 6 cylinder blocks because we found that after bolting the bell housing to the engine pulled #6 out of round. We did that on the advice of the head engine builder for Bobby and Donnie Allison that used the same machine shop as we did back in the late 70's.