Had our last chance at figuring this out on the weekend. Changed the digital 7 out for a known good one and pulled timing out at a slower rate proportionately to boost pressure. Same thing car would hit 4500 and start to breakup. If it spun it would clean up and rev to 7500.

Black smoke? Popping from exhaust, or carb? Any video?

Listen to Monty.

If it was me, (it was last year) Monty told me to run all grounds to a copper bar and ground it to the battery. AND put firecore plug wires on it.
After I did it woke up.

Will try and post a video, but i havnt had one person say there was black smoke coming out of it and i would have to think on the passes it doesnt clear up at all it would be pretty clear. Im not sure if this helps but i was looking back at some data and it seems like the last time the car ran clean i was pulling an additional 10 degrees at the release of the foot brake and ramping it back over 2.5 seconds. I took this retard off because the car was really slow in the 60 and then would knock the tires off further down the track.