I checked the distributor. The phasable rotor was lose AND the distro hold down was loose. I think the whole thing got shook into a too advanced position. I reset everything and put the timing light on it to get the timing squared away
Detonation. That’s usually what breaks the ring lands.
If the engine and cylinder head checked out good then my vote is to replace the piston and ride. I would say get the parts together for a winter project but I don’t think you guys experience that. Haha