Thanks for the feedback.
I got a Powermaster 140, mostly because I did not want to do any more wiring and adapting than I have to.
I am hoping that this: Fits the 1980 serpentine bracket.
Does not require any wire changes.
Does not require rewiring the ext regulator
Does not need an extra set of wires to the cut off switch.
The only prob so far is that I have to run a new switched wire from somewhere to the choke heater, as I had been using the stock Ford unregulated output wire.
I have thought about the 3g upgrade, etc, but my experience with salvage yard parts at this point is that it takes too long to go there, find one, remove it, etc. Especially if it needs to work, not just look good.
That said, I spent 4 hours last Sat in a salvage yard removing tailight bezels from a 66 Malibu to install on mine.
So the Mustang has to make do with new stuff. I can make up wires if necessary.
The 3g does make a lot of sense, and I may go to that on the Capri, when I go with electric fans, or on the 82 if this doesn't pan out.