FWIW, I've found that Italian/Campagnolo lock rings fit Schwinn Paramount hubs. If such are more common in your neighborhood than the Campags. No, I don't know why.
harvey sachs mcLean va. ++++++++++++++++++++++++++++++++ Wayne, If the lockring on your Campagnolo hub was a BB lockring, then it was a road hub, not a track hub. English BB and freewheel thread is the same (1.37" x 24 tpi.) Track lockrings are always smaller than the cog thread, and ALWAYS left-hand threaded.
Campagnolo uses their own lockring thread, and I don't believe anyone else uses it. It is 1.32" x 24tpi LH thread.
Most track hubs are English thread. They use a 1.29" x 24 tpi LH threaded lockring.
French are 33 x 1.0mm LH thread.
If you can't find a track hub but want to ride a fixed gear, you can often fit a BB lockring over a cog on a freewheel hub, and respace the axle to the right chainline. Loctite or equiv. is a good idea with this setup, and so is a rear brake. It seems to work ok as long as you don't try to stop with pedal pressure. If you spin off your cog doing so, you will be in a world of hurt.
Greg Reiche