You may laugh but I have actually had people tell me that was impossible to do as the head was on the block.
You can almost get the same visual aid by putting a small 12 volt bulb in the combustion chamber, running the wires through the spark plug hole, putting a piston and single ring in the bore and looking at the roundness of the cylinder from the bottom of the bore with and with-out the head torqued . Tom V.
