Hi Bushie, you mentioned earlier that the motor felt tight to turn over. I notice the decompressor is blanked off with a spark plug and you have no plug in the plug hole, so it should turn freely with minimal resistance. If you've checked the end gap of the rings and they were within limits i would suggest that you remove the ring expander from under the bottom ring and see if this helps. By your photo it seems as the bottom ring is the one that is marked yet the top ring appears unscathed, hence leading me to believe the expander is causing your problem.. Both rings are still usable as you have not yet turned it over a few hundred times with the drill.

After you've removed the expander and re-assembled, the engine should turn freely by HAND and not require the use of a socket and ratchet.