EC 300 cylinder max wear limit?

[gassumies]

I bought the bike with no history when the piston was last changed.

I dissabled the top end,
turns out the previous owner had installed the A size piston (cylinder is stamped A but the bike is from 2009)

It has some light up and down marks but i cant feel them with my fingernail,
probably from the too small piston slapping around

The cylinder measured 72,03 and the biggest piston from vertex of wossner is for 72,02 bore

Is the coating too thin and break off?
or will the 0.01mm extra clearance cause it to slap around more and ruin the cylinder for good?