The Holley parts are pretty standard and any local parts house should have a rack of them. Holley used two different accelerator diaphragms for the pumps, a 30cc and a 50cc. You can tell by looking, the casting under the pump is about 3/8" thick for the 50, and about 3/16" for 30cc. They will not interchange diaphragms, yet both are common parts.
Get a set of bowl gaskets,
http://www.holley.com/types/Gaskets.asp which you can compare yours to the new ones.
http://www.holley.com/types/Power%20Valves.asp Looking at this page from Holley, you can see there is a bunch of power valves available. Check what is in your carb before purchasing one. The number is the amount of vacuum it takes to open the valve, the small the number, the quicker they open. It works like metering rods, adding more fuel under acceleration.
And for the record, this is not the original carb! GM never used adapters.
Joe
