Fine Tuning a 360 Magnum with a Brawler "Double Pumper"

I mean when it’s hooked to ported vacuum, or “timed vacuum” as it’s called on the diagram. It’s the port that gets the same Venturi as the jets I believe? Manifold vacuum decreases under load but Venturi “vacuum” increases does it not?
Ported vacuum will only see vacuum when the throttle blade is passing it, i.e when you're cruising on the Tslot