Compression check showed 65PSI. Oddly enough, this has actually happened a few times over: a bike starts and runs fine when you go to check it out, but you take it off the truck and it wont fire up because the compression was so low in the first place. it boggles my mind.
Anyway, I ordered new rings and went to put them in: bam. Scoring on the cylinder.
I've attached pics of the 'top' of the cylinder, the part you can see with the piston at Bottom Dead Center (BDC): no scoring there. You pull it, and where the piston sits at BDC is where all the scoring is. Nothing that can catch a nail but it has definite grooves.
Looks totally mucked, mate.
'
What's a cheaper solution: overbore + new oversized piston + oversized rings?
or fresh piston/ring/cylinder combo?

Piston Scoring

Bottom Cylinder

Top Of Cylinder