Actually the holes are to alter the idle air flow/speed, without having the throttle blades open too far, so the transfer slots are not in the correct relationship to the blades. I would try the carb as is (with the holes) and see if you can adjust the idle speed and mixture, properly. Then drive the vehicle, and see if the transition is smooth. If the idle speed is too high, with the speed screw all the way out, you will need to plug the holes.
