Group K is all about reliability and less $$$.
Not sure which carb is really better but I do know Mikunis have cheaper, readily availably, and easier to find parts than Keihins. I need a throttle drum for my Keihin 42 and the only place to get one is Japan... sucks!
I would say a single 46 is a good carb for a mild 750 for the very reason it won't drink a bunch of gas. I really would like to try a single 48 Novi, Riva power bomb, ect...
I figured the stock duals wouldn't been that hard to tune. You were probably in the ball park but with the different exhaust and pump setup ect... have an effect on what jets you need. But you are on the right path. Try it all and see what works.