I have found that a carb change even, if CFM is supposedly rated the same, usually requires a jetting change. Another thing is air bleeds, and the idle feed restriction. I have had to change airbleeds, and reduce the idle feed restriction, ( why do they make the idle so rich, out of the box? ) . So,I suggest, do all your checks, fuel pressure, float level, then check, out the idle fuel restrictions, and air bleeds , and see what you find. You may have too , make some changes. Then watch a video from DragBoss Garage, with Mark Cambell. Mark was a Holley engineer, back in the 70's and explains some of the differences. Hopefully Drew sees this, and responds.