Holley/Demon Carb stumble

I’ll make one comment which may or not prove to be relevant for your situation.

With regards to doing your testing in the garage in third gear.......
This might get you close, but doesn’t actually simulate the dynamic condition that occurs on the track.
As such, I wouldn’t concentrate on the loading up after a 3rd gear whomp until after I knew there was still an issue, with the car actually driving off the line.
At the track, you floor it, the car moves, g forces act on the fuel in the bowls, which changes the effective level in the bowls...... which impacts how the main circuits respond.

And, at the track..... you don’t whomp it, then let off immediately.
If there are no ill affects at the track with a certain carb calibration...... I wouldn’t care one bit if it loaded during a “static” whomp.

I also suspect that some modulation of how fast the pedal is pushed to the floor could show very positive results.