Help decipher GM distributor vacuum canister numbers

[Kilohertz]

Hi folks,

I'm in the process of restoring my 49 Ford F-47 with the 239 flathead, and am starting by getting the engine running nicely. It hasn't run in years, I have it running now and am starting to make some mods.

I decided to start by machining a GM distributor to fit in place of the Loadomatic. It turned out great and engine fired right up...I am now fiddling with the fine tuning of advance both mechanical and vacuum. All of the references I have found are quoting NAPA/Echlin parts numbers, the VC1765 type etc. I have been unable to find any cross reference to the original GM numbers, and of all the GM dists I have here, none of them have NAPA cans in them, they are all original.

Has anybody found a list of vacuum canisters that reference the original numbers such as are found stamped i.e. 503 15? I know the 15 indicates total crank * at full advance but I want to know begin "Hg and final "Hg.

Any help would be greatly appreciated.

Cheers

PS for now I have an adjustable timing light and hand vacuum pump.