I once picked up a camshaft and head for a cb550 that had been converted to run needle bearings, I have yet to install it and see how it preforms, if good I have it in mind to try at copying it. I probably have a good head, but with a few engines awaiting rebuild am not that keen to spend a week sorting that parts stash. I know I have one with bent valves, otherwise was immaculate, wasn't cam cover fitting though, the engine was a Us import and kept killing tensioners, after the second went I retired it pending spare time to investigate bottom end. I wonder could guides be moved accross from a otherwise knackerd head to a good head with dammaged guides? I geuss to even consider it you'd need a reamer the right size to ream the re installed guide. I was told by the seller of my first 550 that bent valves can be streightened - I wouldn't try it given how hard they work and the mess if one lets go.
