[Mike Madonna]

I'm in the same boat you are.... same manifold and carb. Carb has only one manifold vac. port at rear of base, and on my application that is used for PB booster. The other manifold vac. port is under the primary bowl on the pass. side. The ports are different sizes, smaller in the front & larger in the back. I understand that "tapping" the #4 intake runner may lean that cylinder out somewhat.

Mike