Suggestion, carefully inspect the rest of the engine. That damage was caused by something being ingested into the engine or a wrist pin clip coming off. If there are other parts, case, bearings(which I would guess where shot) , head button. that need to be looked at. Check the crank, the crank case, back plate, everything. THEN its time to evaluate the engine. If the rest of the parts are ok, you might just go for a piston sleeve, if your conrod doesn't have to much time on it. you might use that for break in. then throw a new rod in it. But your piston has a LOT of pitting on it from what I can see in the pic. The fissure on the side of the piston is now the stress riser and it will fail from there. Find out how much a new piston sleeve and rod are. and go from there. That's what I would do. That gap in ring seal will make the tuning inconsistent and it would annoy me. lol.

Cheers