Interesting. I wonder if a prior owner hand honed the cylinders, which would explain the hatch pattern and it just got rusty from sitting.
Good luck with the sale.
Def. not hand honed...I had thought that too at first, but the pattern is dead nuts consistant from hole to hole. The tops of the pistons and the tops of the bores have a consistant carbon coating, but there is zero trace of a ridge, and the cross hatch runs right up into the carbon.