hmm...
the problem always is getting materials that can be machined. I once used a car rear axle to make (hand file job) a new side valve engine camshaft with special timing, and I NiCoTrated the soft Veco .19 cylinders to make them glass hard. That made the engine as durable as the best Webra of that time.
I like your idea of using camshafts for piston rings It is a very fine grained material with a lot of shock resistance and excellent wear properties. Car engine materials are the best one can get at scrap prices!
Dykes rings I made out of scrap cast mold meehanite for a ST.25 lasted well in CL, but not very long in prolonged full bore RC operation.
BTW, That ring experience was the reason I asked.