Last year I spun #1 rod in my motor ( this is the furthest bearing away from the pump) upon disassembly I noticed a couple of things. The closer to the pump the better the bearings looked BUT all were in the copper. Between Journals 2 3 4 the cases were flexing and that had to be losing some oil. The rod bearings are the exact part # for oil cooled motors, so I doudt it is really a " bearing material problem"
I disassembled my motor this year after the season was over and my bearings looked good nothing bad or out of the ordinary!!
This is what I did to help the problem
1 high volume oil pump gear
2 modified the oil pump pressure relief valve
3 I put case studs to keep cases from flexing
( I knew the cases were flexing last year because the aluminium was blackend on those journals were the bolts went thru like they were rubbing)
4 all loose bearings on rods only (green )
5 I made a oil line going from oil gallery on right side of engine above the sending unit to the #1 main that feeds the #1 rod. you have to have your engine disassembled to do this because you drill down thru the oil gallery out the bottom of the case, tap the hole run the line and your done..
this may not be the fix all for everyone but it took care of my problems, and I run the oil level to the top of the site glass( I would rather miss 1 or 2 hp than tear up an engine in the middle of the year!