Just went through this to replace a Winner 13-26 on my dear 1978 Proteus. Scoured e-bay for a few months and was amazed at the prices some of the NOS freewheels fetched. A friend put me onto Interloc Racing Design (aka IRD). Check out their site. I bought on of these freewheels and find them much more nicely made than the presumably Chinese made ones you see in the catalogs. I happen to run a Campy 9 speed chain with no problem, but suspect you don't have big issue with this.