Quick Fuel Secondary air adjustment

[RET_COP]

AC Ventura you stated, "I’ve read about drilling holes in the butterfly’s to introduce some air," NO, not yet at least and is last resort. There is a lot more to consider. You may be OK right where you are. The plugs won't read properly now that you have them carboned up due to a previously bad idle mixture that you may have fixed.
Stop where you are, drain the bowls take the carb off and flip it upside down. Look at the throttle blades and the relationship to the transfer slots. Particular attention to the primary as you have stated you have a good idle. the edge of the plate should be in the length of the transfer slot maybe exposing about .020" [ it would look like a even square]or so. The secondaries will maybe only expose none to about .020 of this slot : this would be a good balance. If your idle adjustment screws had an effect on the idle chances are they are in the functionable window. I usually go for a balance with a little less exposure on the secondary side if I can. Drilling the primary plates come into play if by getting the engine to idle at desired rpm the throttle blades are open too far and out of the range of the transfer slots. Holes will cause a higher idle forcing you to close the blades and bringing them into the functionable window of the transfer slot. I hope I explained this well enough. I'm not too good at getting my thoughts in my brain onto paper sometimes.