If your closing the choke (less air, more fuel) then your needle setting may need to be moved (clip down, needle up = richer mixture, I think....)
You could try the shut off test. Cruise in that bad zone and then kill the engine and check the plugs, do they look lean? Then move the clip, clean plugs and repeat, if the ride and plugs improve, your on your way to tuning the carbs.
I was doing this test w/ mine when I was running pods, it was getting there but I finally found an airbox and went back stock.
I dunno about the 750 carb needle removal, mines a 550. In mine it's easiest to take the carbs off. Oh the joy
-Tim