Well I figured I'd hear from someone who'd done this but I guess the really fast guys are keeping quiet! Onward ho with 44 flat slides (at the very least)!
I have tried several carbs over the years. 40mm max for trail (bored flat slide so the pull is easy) you can use much larger for race only. The stock intake manifolds will stretch to hold most larger carbs. They also have the angle correction designed into them.
This is for full throttle wide open racing! I know 44s will work just by the stuff I know guys run on Banshees. I figured maybe someone on here had done it and then I could pick their brain!