The rings do the sealing so their condition and operation is important. The ring grooves (lands) mustn't have any rough spots that prevent the ring from laying flat or that force the ring out of it's groove.
Get a tiny file and smooth over the scratch(es) and damage in the lands and between the lands and it should be ok. But without seeing how bad the actual damage is, it's hard to say if more should be done.
I've run pistons that were beat to hell with deep scratches from top to bottom after filing the scratches somewhat flat .. As long as the rings are able to seal and the piston doesn't smear aluminum along the sides of the bore, it's good enough for the average trailer park get-me-to-the-store-and-back moped.