spacetrekker

Hey sherpagorri, not sure if this will help, but way back in the 70's I modded a SL100 engine, including having bushing inserts made for the cam. On that engine, the cam rode directly on the machined head surface. The bushings were made out of aluminum and had a groove or hole for oil passage. I don't know remember the specific details but I'm sure the original internal (right side) surface was machined for the insert without boring through the head. Look for another machine shop that specializes in smaller engine work.