When changing camshafts in an engine you have also changed the engines air fuel needs. At all throttle and rpm points but most noticeably at idle.
Due to the higher lift and longer duration of your new camshaft, your current carburetor whether it is modified, or a stock carburetor (even though it may be NEW) may not have enough mixture necessary to provide the engine with, for a smooth idle and transition circuit. If you have found it necessary to turn up the idle speed screw farther than normal, exposing more than .040-.045 of the transition slot, then you will need to modify your carburetor to suit the modifications that you have done to the engine.
Consult ACFI with your options for getting your carburetor set up properly.