Thanks again all. I hope Matt/Maybellene/Shop Shark will sell me his pair as they look to be just the thing. A NAPA gasket set for mating to the head comes with a gasket for the manifold pair mating, so I should be good there. I don't really care about casting numbers unless they imply some characteristic that affects their doing the job without alteration.
Combining DaveV's comment about height of carb mount on the intake with Mark's about matching exhaust and matching intakes separately, is it possible that Mark's intake is not best for a 261 2-ton? In this case, maybe I should try to follow Mark's suggestion.
I will try to move the conversation to the swap forum or the PM thing I just learned about. Again, thanks!
Clarke
