nice job and thanks to all who worked on the carburetor report
have not seen those 2 BB for a long time
In the mid 70s I had a daily driver 68 El Camino 350 4sp and was trying to improve fuel mileage.
Replaced the 600 Holley with the larger 2 BB on a home made adaptor plate on a alum intake and home made manual choke setup.
Once I got the jetting right it Worked pretty well. Was very smooth like a fuel injection car with no secondarys to kick in