I have to wonder, the fact that it had 160/164 to begin with, what the history is on it. I would pull it down and check #'s on metering blocks, all E-hole bleeds, main intermediate and idle bleeds and check booster hole diameter against BG's website I posted. Sounds like someone was doing some changing before you got it an have it all messed up. Otherwise send it to BG to check out.

Could you have some problems with the air bleeds to the bolsters?
It seems with your smaller carb, you are getting a better signal thru out the range, It is possible with the larger carb, you are not getting the top end signal correct. I am not sure on those carbs, we run Pro systems and they have changable bolster bleed jets.
the smaller the jet the more fuel you will flow ( Air Bleeds )