I think that the issue with the Progression unit is that there are two Pantera screens. The original all wire screen is a tighter fit then the later with the fiberglass dome cover over the air cleaner.
That one probably has more room for the distributor cap.
In any case, the small cap Ford (Motorcraft) is going to be the most compact distributor.
The big cap doesn't clear the Weber carbs. In fact, back in the day, many Mallory distributors were run with the Webers to reduce the possibility of arching.