..Integrating the double pump carb into the stock control system will make it difficult to know when the best operation is being obtained. There are two ports in the carb casting. One is above the throttle plate and one is below the plate. If you are hooking direct from the carb to the distributor, the above plate port is the one to use. You would not want full vac applied to the dist. full time or it would stay in an advanced state and only retard as the throttle nears wide open. I am referencing a single diaphram vaccumn unit on the dist. Block off the unused port at the carb. Hope this helps with the project.
Good luck, Ken