Map63Vette,
Thanks for explaining the MSD MAP sensor function. I doubt spark advance has anything to do with it stumbling or dying on acceleration since "vacuum advance" is usually pretty small and many racers don't even use it.
I have a Holley 2D Projection on my Newport 383, plus a Holley "Rich/Lean Indicator" box tied to the same "narrow-band" O2 sensor. Not sure why they didn't include a rich LED in the 2D box like in the older add-on O2 controller for the analog box. You do similar by connecting a multi-meter to your O2 sensor. Might be slower to read than an LED unless yours has an analog bar, but sounds good enough since you see the voltage dip near zero. If anyone uses a voltmeter with a needle, make sure it is an amplified type that gets power from +12 V. The older gages with low input resistance would damage the O2 sensor (at least the earliest ones).
My Projection is so erratic that I have much experience with how lean or rich feels. As you say, lean makes the engine feel like it is starved. As you press the pedal, it stumbles. If I turn the Projection knobs it makes a big difference. Just a slight turn and the engine will go from stumbling to pulling hard. If even more lean, when you press the pedal it will give a slight pop and die. Even at that setting, if I pulse the pedal it doesn't die because the "accel pump" function kicks in. BTW, my Lean/Rich box has 3 lights (red = rich, green = OK, yellow = lean). I have only seen the lean light a few times, even when it is stumbling and almost dies.
As you say, when too rich it feels like the engine is bogging, but it doesn't tend to die as you press the accelerator. I don't see any black smoke, but maybe people behind me do. Long ago when I had the original Rochester 2-barrel on the Newport, it once stranded me at a motel when the plugs became fouled with a thin coat of soot. That is what too rich will do. Now I want an O2 sensor on all my cars because I hate "flying blind".