Well apparently this is far from your first rodeo, but it surprises me those metering plates are legal. This is what the rule book says:

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.

Are the plates just something they allow?

Good Luck,
Bill