I am running a 2 carburetor manifold on my GMC 248 and using Rochester carbs. I have choke cables to both carbs and find it necessary to use both to get it started. When you only choke 1 of multiple carbs the vacuum transfers to the other (not choked) carbs and there is no benefit to choking. Only my experience, but I had a GMC 270 with a Howard 5 carb. manifold years ago and had no chokes, just one pump with 5 accelerator pumps gave plenty gas for a cold start.
