[Dead Parrot]

Agree with the water sitting in cylinder thoughts. The piston scoring probably happened on the initial start when the rust was being scraped off the walls in both directions.

Might want to flush all the oil passages in case some of the rust escaped past the filter.

Fix might range from something as simple as a good honing and new rings for something that will see only occasional use to boring out all the cylinders and installing new oversized pistons.