Well I went thru my plastic for a makeshift feeler gauge- found one that measured .032" on the first try so I went with that. So the Pertronix sensor got gapped and got the distributor back into the car. Started it up and let it idle for ~10 minutes to let it warm up and to report:

1) After warm-up, I had a very smooth idle and the off-idle acceleration stumble is almost completely gone. I seem to feel a slight (very slight) hesitation but I don't know if it's my imagination or if I just need to re-fine-tune the engine again (I did not reset the initial timing on the distributor - I just lined it up with a set of marks I made before I pulled it- but I imagine I will have to since I've effectively changed the dwell). The idle is much more stable, too- it was idling at around 500-550rpm once it warmed up (and it's NEVER idled smoothly at that speed before) and I had checked the RPM- I reset it to 750rpm and reset the carb idle screws to 1-1/2 turns out as I'll have to fine tune them, too.

2) In another thread I had mentioned a 'sticky' accellerator pedal, which I did not experience while doing the above. I'm not 100% sure it's gone away and if I inadvertanly fixed that issue I certainly don't understand how what I did would've affected that issue.

Anyway, in a day or 2 I'll get around to doing the fine-tuning (as well as doing the rotor phasing test) and I'll report in again.