When you have wear on the uppers that can mean that the engine was getting into detonation. Maybe from your recent experiments?

The mains may have gotten chewed up from debris in the oil from the rod bearings but usually it's the other way around. Having gouges in your mains that line up with the oil holes is a strong hint that garbage went through. Have a real good look at everything, including your oil filter - you did save it, right? It might hold some valuable clues as to why your bearings started to fail.