'70 C10 Converting Vapor Can to Standalone Purge Valve

[Gromit]

I have the first year of the C10 with the Evaporative Emission Control ("EEC").

This was a California thing at the time; so the Vapor Canisters for the 1970 are no longer (readily) available.

The vapor cans for 1970 had an integrated purge valve and I read that the carburetor was jetted to take into account the orifice sizes and spring pressure of the purge valve diaphragm.

In later years they went to a different design of purge valve; sometimes electrically controlled, sometimes vacuum, sometimes integrated, sometimes not etc. But the short answer is that the Vapor Canisters that are available today are not generally backwards compatible to 1970.

Today I found a Napa Echlin emissions catalog and noticed that they do have standalone vapor canister purge valves.

So I am thinking of just installing a late type vapor can (that does not have the integrated purge) and then adding a standalone purge in between the canister and the various PCV, Ported vacuum and fuel tank hose connections.

So before I try and reinvent the wheel here has anyone with a 1970 California EEC truck already gone down this path who is willing to advise which Echlin parts to use?

I'll attach the Echlin catalog pages of purge valves and then of canisters (or at least the canisters where the catalog mentions Chevy Trucks)