New ignition, new stumble

[Moriarty]

Symptom: On quick accel from rolling, the engine hesitates then surges. Not sure if "stumble" is the correct term?

What changed: I just picked up and installed a programmable timing distributor from Progression Ignition to test out (was interested in adding vacuum advance). Was previously using a MSD 6AL box w/ MSD Blaster 2 coil and MSD distributor for magnetic pickup (no ballast resistor).

I'm currently bypassing the 6AL box entirely, and have the new distributor wired up to the existing coil. PI says the Blaster 2 should work great.

My limited understanding of timing doesn't seem like this is a symptom resulting from improper settings.

I'm wondering if it's a side effect of switching from capacitive discharge (CDI) to inductive spark? I forget what I gapped the plugs to, but haven't made any changes so maybe that needs adjustment now?

Prior to swapping out I was adjusting the carb and have things pretty lean, but was working well with the MSD distributor/box.

Suggestions?