Ian, you have a good point about the wear but I still think you have to consider all of the 1970s CB-750s that are running over the road now and still show minimal wear. Then there's also the 100,000 mile Bonnie that was reported earlier this year; I'm not so sure that after 100K miles that replacing the head would really bother me too much, at least not as much as replacing the ignitor at 10K did.
I was trying to think of an overhead cam engine that actually uses a separate bearing and I couldn't think of one. Anyone? I can only recall pushrod engines that use cam bearings, but that just be my limited exposure to overhead cam machines.
And, Matt, I've only been in the cam chest once but I don't think I saw enough meat to retro fit a decent bearing. But it would be a great idea to be able to line bore and fit a caged bearing, just think how bullet proof that would end up being.
