Given the two choices with you have listed, I would suggest rebuilding the "B" for the following reasons:
(1) The 292 carb is internally larger, which would add more power at the upper RPM ranges, and SUBTRACT it from the lower RPM ranges.
(2) The gaskets/accelerator pump/fuel valve used in the N.O.S. 1967 carburetor are NOT compatible with modern fuel, either ethanol-based or real fuel because of modern additives. It will require rebuilding before use.
(3) There is always someone who doesn't understand number (2) above that is willing to pay big money for N.O.S., especially a 292 carb.
I would suggest a third possible option of looking for an appropriate Carter on Ebay.
Jon.
