I have been looking at your photos and can not see any damage to the piston top. Usually when a ring breaks the top of the piston where the break is deforms.as the broken piece pushes through. What may have happened is the overheating had caused some oil to burn off the cylinder walls and the piston deformed at the ring grooves, wiping off aluminum onto the cylinder walls and welding the ring compressed in place. I can see what looks like aluminum rub-off on the cylinder wall.
Your next step would be to take off the carb and manifold, remove the rod cap bolts, and push out the piston and rod. Be certain to account for all 16 rollers and both cages.
BTW: Where in PA are you? Close to Philly? I am in West Chester, about 30 miles west of Philly.