Holes like that are usually done on an engine with a wild cam to get more airflow so the idle transition slots aren't fully exposed by opening the throttle to get an acceptable idle speed.
If they are steel I weld them on the carb with a MIG on low.you have to be comfortable doing this and get it done quick and neat.Obviously no fuel in the carb
Throttle shaft screws are staked and this
needs to be filed off and or drilled. Brass screws or sometimes steel ones will shear off making a mess of things.
4412 Holley is a fairly large carb for a 200 inch mild engine.