As much as I love Bing carbs, the replacement costs are crazy! We have been using 38mm Mikuni's on the 414's for some years with good results.
This is the baseline jetting we start with for 2000 ft elevation.
Main jet-350
pilot jet-45
needle-6FJ6
needle jet-166 Q6
standard 2.5 slide
removed air jet
We also install a UFO slide insert which smooth's the airflow on the bottom of the slide. Adds a couple of horsepower.
All of this adds up to about the same output as the Bing, but with much less problems.