RE: OS Camshaft plating peeling
Assuming this second hand engine was a relative bargain you may as well just clean it up and fly it. Consider it a real life test of how long the engine will run. I bet you'll surprise all the local engine experts at the field when it goes well beyond their estimated time to failure.
I had a 46AX that finally ate it's bearings, destroying the piston (but not the liner) in the process. I've since had a GMS47 in the same plane for a much longer period.
Everyone at the field told me I should stick with OS engines as the GMS were rubbish. Well, the GMS outlasted the OS by a clear 12 months before it too had bearing problems (at least this one didn't do any damage). The GMS made more power but, admittedly, didn't do as well as the OS with extended idling and very low throttle behaviour.
Still, and this is not an attack on OS, the GMS engine was more powerful, longer lasting, and cheaper than the sacred cow OS engine that ate it's bearings in a disastorous way. Some engines are better than others and, it's not always a case of the brand name on the casing or how superfine the finish is.