First I really appreciate the information you guys are giving me. I like the suggestion of finishing a proper fuel supply before going further. However, I guess one question to ask at this point is, is it worth it? Visually this engine is in great shape, and the rotor/stator section looks great as well.
Does anybody have any experience retrofitting a decent stator/rotor with new controls, i.e. replace the boost, excitation and maybe voltage regulator with something more modern?
In the meantime, it will probably be a few weeks before I get the fuel system in place.
I'm not sure where to start looking for the boost circuit. Would it be a dedicated board?
If the engine runs good and the all generator windings are OK, it is "probably" worth fixing. The Generac brand VR is readily available if you find it bad. Even if your excitation (DPE) winding is open, there are aftermarket generic replacement VRs available (about $200) that do not need a separate excitation winding.
There are generic replacement engine controllers available, but there is no reason at this point to think there is a serious issue there. The engine troubles you report appear fuel related.
(going from memory here, so anyone with more accurate info feel free to jump in)
The "field boost" applies voltage from the engine control board to the "+" brush lead (usually via a resistor), so look for its lead tied to/under the same lug as the + lead from the VR. Often just another wire with a series resistor and maybe a diode tied to the VR + terminal. Field boost is Generac's term for auto-flashing.