First, thanks for all the helpfull response to my many questions about the ignition switch/armored cable/coil assembly, which is now in place and ready to be wired up.
BTW, Danny, at least in this case, the PV and Amazon armored cables turned out to be the same length.
Next quandry: the donor was rigged with a, safe-your-key, push button starter switch which I also pulled, clipping the wires to help me figure out how to wire it into my car. Looks pretty straight forward. The fat, power supply, red wire that normally goes to #54 on the regular switch, goes to one terminal on the push button, and the green wire that goes from #50 to the starter solenoid goes to the other. So far so good. However, the green wire has another wire spliced into it that was somehow connected to the regular switch. The two switches were held together by that wire but, while I was removing crud, they came apart, and now I can't figure out where that wire was attached to the regular switch. The weird thing is that it has a washer soldered to the end of it (the hole in the washer completely filled with solder), almost as it had been soldered to the switch's housing, but I can't find a mark on the housing, besides, it doesn't make sense to gound the green wire. Any idea what is going on here?
Bob S.

Bob, can't tell you color codes or terminal numbers, but I bet you'll find that one of the switch terminals outside of the armored cable is "hot" in the RUN position.

Run a wire from that to one side of the pushbutton, and a wire from the other side of the pushbutton to the starter solenoid.

Right, that part of it was clear to me from the beginning, and I'm not having trouble with the terminal numbers or the color of the wires -- the cut off pieces of the original wires are still attached to the push button. It's just that silly wire spliced into the green solenoid wire (it could just as well have been attached to the solenoid-side teminal of the push button) that has me baffled. It's only six inches long, so not long enough to reach the coil to get around a ballast, as George suggests, and it was clearly attached to the regular switch when I pulled the whole mess. I'll just hitch the push button up like you say, ignoring the spliced-in wire, and see what happens. Thanks guys,
Bob S.

Or you could just run it from the "run" hotwire to the "start" wire on the
switch so it would also work normally.

The extra wire might go to the hot side of the coil to bypass a ballast (if
any).
--
George Downs Bartlesville, Heart of the USA!