I think they are a high compression set. The raised part goes up into the combustion chamber. I have no idea how much they would raise it but within reason more compression is better.

My Perfect Circle catalog shows these bearing numbers. A counterperson should be able to cross reference them if needed. Rod Bearings # CB427P Undersize P10 P20 P30 P40 Main bearing # MS428P Undersize P10 P20 P30 P40

"I wonder if God created man because he was disappointed in the monkey?" Mark Twain