Siegmund,
This is not strictly relevant, but is a similar situation. I once had a tri-power setup on a 348.(3xRochester 2 bbl.) The center carb was the only one with choke, curb idle and vac.advance. The front and rear carbs did not have any of that and were on a progressive linkage for power only. I guess that backs up what the guys have been saying, although it's a bit different with twin carbs on a 6.
