You can do that on just about ANY vacuum advance. Just try a few different hey keys until you find the one that fits.
Now...what I want to know is: What's the best way to measure when you've got enough vacuum advance coming in. I'm not talking about the standard timing check. I'm talking about making sure you've got this vacuum advance setting properly adjusted.
Some '65s aren't adjusted using an allen wrench but with shims with holes in them (fancy washers). These vacuum advance diaphrams have a hex shaped housing with a fitting on it which can be removed so as to add or delete washers. I had to do this on the one I bought for the replacement single point distributor on my GT with a T. I guess an engine used to '60s premium gas doesn't like 87 octane unleaded!
Set timing at correct idle no vacuum.Put hose or line on.All but 351-C OFF IDLE VACUUM ONLY!!!Full advance at 2800 to 3200 rpm.(basic stock or slight mod.)Lower on very high per.engines.Scott 936-756-2535