This statement was took out of a thread that I found. I would have posted the thread but it wasn't truly about water pumps.
Bill Mock in Oklahoma City is the best-known water pump rebuilder/restorer for the Corvette guys, and will usually have dated small-hole 326 pumps available, but they aren't cheap. Bill has been doing Chevy pumps for 35 years, and is at (918) 333-0748, mockauto@aol.com.