Holes Drilled in Bottom of 1964 R2 Carter AFB Serve What Purpose?

[CarbDoc]

I am confident that someone on this forum can help me with the below issue.

I am working on a Carter AFB model 3725 for a 1964 R2 Avanti.  It has two vertical holes drilled vertically into the carburetor from the bottom, into the "wells" where the air valve counterweights rotate (see two black arrows in photo below). 

These holes appear to be "field-drilled" (as opposed to "factory-drilled"), but perhaps this was done for a good reason . . .  such as allowing accumulated gasoline to drain out of the counterweight wells before re-starting which could lead to a fire if the engine backfired.  Maybe it was a field update in a factory service bulletin?  I just want to be certain whether it is a good idea to plug them, or better to leave them "as-is", particularly since a blow-through supercharger is involved. 
 

I have performed  plenty of "field updates" to carburetors in my career, so this is why I hesitate to just go ahead and plug them. 
 

Jeff