1968 340 AVS 4425S carb problems

Thank you bugman, sorry for the late response a lot has been going on recently. With the shorter screws that are recessed are those idle air bypass passages meant to be open (1968 carb with recessed air fuel screws vs the 1969 style that you pictured above with the air fuel screws and springs not recessed)? Also the off idle adjustable air bleed is unplugged, and did not know there was an adjustment there for we did not see it. The carb was rebuilt a while back and we do not know who did it and how long ago. With the adjustments we made the idle has had less variation and preforms better. With the plugged air bypass drilled out would the car run better and/or preform better?

Thank you
Joe