Read pp.58-62 of this document -
https://www.nhraracer.com/Files/Tech...edProducts.pdf
Also, from the Rule Book, Section 11A, page 3:
"CARBURETOR
Must be correct year, make, and model specified for car’s
engine; fuel or air bleed passages may be resized. Drilling idle
holes in primary throttle blades permitted. Other modifications
prohibited. Sandblasting, grinding, flash removal, dry film
coating, or any other modification to carburetors prohibited.
Replacement carburetors permitted provided they are
same model, type, throttle bore, and venturi size. Computer
carburetors use latest model non-computer carb for engine
application. " (Emphasis mine)