Moving the clip changes the fuel mix by a factor of 5-8%. So maybe in Mikuni terms that's a skosh over two sizes, rules of thumb aren't truly precise and VM jets aren't available in 2.5 increments, only in 5s. Still every move he makes is 8% of 190 at the baseline. 8% of 190 is slightly over 15 and that's three jet sizes. Or it could be 5% and thats 9.5 so it's two jet sizes. Damn rule of thumb variance.
It is true that the main jet determines max fuel flow at WOT but it also determines the baseline that the needle begins with, nothing can change that fact. Then the taper and clip height come into play.
Bottom line, all of the circuits in a Mikuni interact except the "enrichner" which is a totally independent circuit.
Ref: chart 13 page 9 Mikuni tuning manual