[700rpm]

It sounds to me like you are way overthinking the problem. I don’t know about volts here or volts there. This is a simple car, and I’m just a shade tree mechanic. But I have played with and worked on these cars for over 55 years, so I have some experience. Timing your A is a basic function and a necessary skill if you own a Model A. No need to be afraid of it. It takes maybe 10-15 minutes. It’s worth it just to know if the pigtail is shorting out (which it often does).

I suggest: Pull the distributor, disconnect your ignition cable, and turn the key on. Then scratch the end the cable on a head nut. If you have spark, you have current going into the dissy. Shut off the ign. Put the cable back in. (But not too far). Check the pigtail. No contact with the body (so no short)? Reassemble. Replace the dissy in the head. Turn the ign. on. Open and close your points. You should get a spark at the points. If not make sure you have the proper insulating washer under the point block. If you have spark at the points, reset the timing. Check for spark at the points again. If you have it, you’re good. The basic requirements to making a Model A start are fuel, spark (ignition) and timing. With those, and fundamental clearances and settings, the car should start.
Your car was running OK before this problem. Mike V’s and other suggestions are valid, but do the easy things first. The answer should be simple.