The shape of the IDC restriction doesn't really matter, it's location does. We sell channel restrictions and main airbleeds. They are slightly chamfered on the outer edge on one side to help get them started.
The small holes just below the nozzles should be left as delivered, as should the holes in the end of the brass nozzles. They are part of the carburetors original calibration, and both have a small impact on fuel delivery to the engine......Cliff