Vacume advance canister

It might be easier to make you own adjustment. I did this in the late 70's. Vacuum pulls the arm back to the canister. The arm has a tab that serves a stop, two holes for 4-40 screws can be drilled and tapped, to add a small plate to serve as an early stop. With it you are limiting the advance at maximum vacuum. The screw in the nipple only changes the minimum point where the advance starts.

It is possible to estimate the stop. If you know the total travel, and the degrees for that. Then limit the travel for what you need.