IMO, you spent a lot of time trying to make something work that was totally not right for the engine.
If CFM was a trade-off, and bigger carbs always made more horsepower, then most of my customers would be putting 1450 Dominators on everything.
Carb CFM follows a rule of diminishing returns. A bigger carb doesn't always make more horsepower. I think you could slap a smaller carb on there, not notice any WOT power difference, and gain lots of happy street manners down low.