You'd have to make changes to the lines. The Carter has a bigger body than the AC, and the ports don't line up the same.

It could be one of many possibilities, or a combination of issues. You've done the first, to swap the plugs. Next check the firing order. They run surprisingly well with a few wires swapped. Then timing at idle, and at part throttle, and at 3/4 throttle (you'll need an adjustable timing light).

If all checks out on the ignition side, isolate carb functions. Make sure you don't have a vacuum leak (hollow stud uncapped, loose base nuts, bad vacuum line, etc.) Use a vacuum gauge. You should get 15" or more at idle. If not, find the leak. The idle speed screw should be in just a small amount, if it's open too far to compensate for a vacuum leak or late timing you'll get the stumble.

Step by step. Keep notes of what you find, what one item you test, and what the results were.