Looks like you head gasket was leaking. Time for a de-carbon too. Use a wooden stick.

24:1 or 30:1 synthetic oil after will keep that to a minimum.

Piston skirt scuffing is usually from "cold seizure" where the piston expands faster than the cylinder walls because of too much load/revs too soon before the engine is fully warmed.

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If it ain't broke, and you mess with it long enough, it will be.