Hey Casey
Does it have a idle speed screw on the back throttle shaft, most 4150's dont but some HP series do. Some you can adjust with the carb off on the bottom side of the base with a small set screw. You can turn it in a 1/2 turn or so. This will help give the engine some extra air without being so much in the front transfer slots. Thats why you see lots of old holley out there at the swap meets that have holes drilled in the butter flies. If you dont care to do this, this still might be a option, you can get replacement butter flies cheap if you want to go back so..
Make sure the floats are close, back the idle speed screw all the way out, then turn the idle mixture screws out about 1 1/2 to 1 3/4 turns from a light seat. This is probably hair fat but should provide a base line to adjust from. Turn the idle speed screw in to it just touches the cam, then turn in 1/2 turn see if it will idle, if it wont turn it in another 1/4 turn and try again.