Does this piston need replaced? (see pic), Dropped exhaust valve from broken spring Options

[dfelz]

Had a valve spring failure on cylinder #2 exhaust, engine was cut very quick after the noise since it was in the garage undergoing tuning when it happened so wasn’t on the road driving, and I’m assuming thank thankfully mitigated worse damage. Just got the engine dropped and the head pulled off for the first look inspection. There are minor scuff marks on the piston head, which could be sanded down and only leave very minor scuff marks remaining is my guess from how it looks and feels right now. But would like the opinion of others if this is the route I should go, or should I just replace all four pistons (since I believe they are only sold in sets)??

As for the valves, should I replace all my exhaust valves anyways while I’m in there? I thought I remembered reading at some point that the exhaust valves have a shorter life since they see more heat. I don’t see any damage to the valve and the valve tube still feels perfectly snug with the valve stem. Any consensus on this front? When I rebuilt the engine 8 years back (was only running for first two now been sitting since then) I can’t remember if the valves were replaced new, I can see from the old pictures the springs clearly weren’t new, hence me now having to deal with the broken one...

Any comments appreciated, thanks