Carb. Mechanical or vacuum secondaries?

yep. You drive off the front barrels, and they are set up just like a VS front barrels. I don't know why so many attach VS to fuel economy and DP for being race only.
Cause people get into the secondaries and secondary shooters much more with a double pumper.
I tend to look at rear gear as a hint .2.76s? V.S.! 3.91s? D.p. Torque converter is also obviously a factor. Your 3.23 are a good compromise, you can probably go either way.