I would just remove the choke flap & assembly, at that point milling off the tower IMO won't gain you much to speak about, then you have a carb that can't have a choke anymore , You can get bigger air flow in booster changes/modifying or opening up the venturies.

75 Duster, 451 10.87 @ 123.58 NA 97 Z28 6sp., 12.01 @ 115 on a 100 shot 71 Swinger. 360 magnum. 12.58 @ 105 78 cutlass, 469 BBC. 12.70 @ 108 on street tires. http://www.youtube.com/watch?v=Z2kqNmMfheU