Quintface - I haven't double carbed it. But I have an AFR gauge on my bike's exhaust. If you could afford a brand new replacement original carburetor, that would be the way to go. The stock carb (if fully clean) is WAY MORE than capable of supplying this bike all the fuel it needs and then parsing that delivery down as needed for good performance throughout the spectrum. Of course, I'm not certain what problems you were having to go dual.
2016 Honda Rebel 250 - The "Piglet."
AFR sensor equipped and downsized to a 0.105" main jet.
The only changes so far.
Bought on 6/29/19 with 44 miles.