Holley stumble trouble

The old Holleys calibrations are usually close - just need a little tweaking.
The new stuff often has newer, but not neccessarily better ideas baked in from the start. So its a pick your poison situation. For someone who knows they will be adjusting restrictions and bleeds, that's tips the scale toward the new shiny. In terms of cost, an old Holley you already own is hard to beat when compared to the priceds of new carbs these days.

There is another option on the MAB and IAB restrictors. Press in new ones. BLP had the blanks - hopefully they still do.
Years ago I paid one of the guys turn a couple in the machine shop. (Like many shops in a larger setting, the machinists could do their own small side jobs on their own time.) Should have had him make more - like a dozen!

Obviously this isn't an easy change option, but if your close and drilling up, then need to close down, its a nice solution instead of having wires permanently in there.
On a carb with choke tower, tapping and using a set screws is a PIA. So this is the situation where IMO its worth considering the press-in option.

my ,02