The purpose of the throttle blade holes is to allow the same air flow at a smaller opening of the throttle plates.
Fuel through the idle circuit is delivered because of the air velocity of air passing the slightly open throttle plates. If the plates are too far open, the air velocity decreases, thereby allowing less fuel flow from the idle and off-idle circuit. Having the holes will allow some air to pass through the holes, less air to pass the throttle plates, but at a higher velocity.
(Opinion) plugging the holes will significantly hurt your idle quality!
Jon.
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"Good carburetion is fuelish hot air". 
"The most expensive carburetor is the wrong one given to you by your neighbor".
If you truly believe that "one size fits all" try walking a mile in your spouse's shoes!
Owner of The Carburetor Shop, LLC (of Missouri).
Current caretaker of the remains of Stromberg Caburetor, and custodian of the existing Carter and Kingston carburetor drawings.
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