More often than not, a carb or Weber problem is an ignition problem.
I also had MASSIVE spark scatter with the Pertronix and 009. The whole reason I did the Megajolt crankfire ignition. Nothing else fits with a 911 shroud. Mallory, Pertronix, all the bigger distributors don't fit. If they do, great for you, easy fix.
Now it purrs like fuel injection. Of course, after a few burps and farts during the warmup-without-chokes period.
Good on you, Mitch!