Try putting a post in the parts wanted forum. Aside from a tour of your local junk yards, that may be the easiest route.
Anyway you slice it, the upgrade to 19.5 wheels wont be cheap, but I think it is the best longterm alternative. What I found when I looked for mine was that while used wheels were available, they would not accept the original style hubcaps for my 51. If I kept looking I may have found the right wheels, but I ended up swallowing hard and bought new custom wheels; they look great and should outlast me. In my evaluation, when I considered the time to find them, cost of replacement hubcaps (I had none), cost of shipping, reconditioning, the new wheels weren't that expensive. I was fortunate that the mfg happend to be located not far from me, so I avoided cost of shipping, so that helped too.
