both carbs are from the same application
This is true, and unfortunately a pretty common problem.
If the carburetors have been apart, they may no longer contain all the internal bits called for on the tag. There are several different metering rods, power valves, venturis, body or throttle castings with drilled idle passages that can be swapped but will not run the same.
If you buy rebuilds, make sure they can be returned or exchanged.
Carburetors that fit the SAE #3 bolt 2-15/16" pattern are probably a bit big for dual use; the smaller SAE #2 2-11/16" pattern will identify a more suitable size such as from a 216.
The smallest venturi "B" (smaller than the original 235) with your bolt pattern is from the Gen-3 230 motor.
