You asked for the best......
Not the cheapest.......
Example: the t/shafts are mounted on ball brgs, last forever, no air leaks to give mysterious idle problems. Plus lots of other features, that is what you get for the extra $$$.
Well.....he kinda asked a very specific question and I'm not sure he knows HOW specific himself.
His question was "best 2bbl carb for the super six"
To that question, there's only one answer and that's the Super Six carburetor. Anything else and it won't be a super six anymore, since the super six is a specific factory package that only came with the Carter bbd. So, that's the only choice, or else it's not a Super Six anymore, rather a slant 6 with a two barrel carburetor......of a different sort.