I'm not so sure I'd want to bore them out for a bushing. They don't have a lot of extra material to begin with, and I'd be afraid of weakening them too much. You may want to consider honing them to smooth the galling and get about .005"+ clearance on the shaft. Then use them on a motor with full time oiling to the shafts, preferably not from the cam bearing oil feeds.

Mike Beachel

I didn't write the rules of math nor create the laws of physics, I am just bound by them.