Your reasoning is sound. Experminenting will prove whether its the actual issue.
The transfer slot open to .045 at idle means the slot is contributing a large portion of the fuel at idle closed;
And then runs short of fuel as the throttle opens past.
IMO, experiment with the smaller t-slot first.
Then depending on how that's going, measure the primary idle air bleeds. Then stick some .020 to .030 wires in them. Loop the wires down under the air cleaner gasket. That's a quick an effective way to make the idle -especially the transition - richer.
You can do the math if you want to figure the new equivelent IAB diameter with the wires. Calculate the area of the current IABs. The area of the wire. Then subtract and figure the diameter.
