It has weird patterns on the cylinder walls. To get it to 420 CI. The piston is almost a hockey puck! Not much skirt with gapless rings. Not to hijack. Didn’t smoke just a bunch of crankcase pressure.
I've seen etching like that before. The oil company that made the oil he was running used a cheap additive package and it would etch metal like that. I'm betting if you look at the rings you'll see some etching there too. Plus some on the lifters and other places.
