Greg Parker wrote....... freewheel cog (it's flat here in the my area) are the later six-speed Winner freewheels and Sedisport chains. The narrow Sedisport works well with the vintage narrow-caged Campy (and other) front ders., and shifts well due to its "bulged-link" design. A bonus is that neither of these components is particularly expensive.
I rode that setup as a daily rider for years, as long as you have all the adjustments correct and everything well lubed you will be right. One thing I did have was the angle of the RD a bit forward, you get a better shift if the body is not so vertical, but you do loose on the max size on the freewheel, but I am also on the flat, so a 21 was large enough at the time, you just have to be brave to either grind the stop on either the RD body or the dropout.........regards wayne davidson Invers NZ........wet N windy......