Thanks for that info. Those two remaining wires (actually four, if you count the two grounds) must be the ones. I already know the purple is for pre-ignition and the yellow, which I have not tested yet, is hopefully for the starter. They are in the passenger footwell as part of a 14-prong wiring harness that is attached to nothing. There is also an 8-prong harness, also connected to nothing. I suppose the original alarm, and some other factory-installed device were there.
I will not be installing a new alarm, but will probably put a blinking LED on the dash, as well as investigate a fuel pump kill switch.
I stopped working on it once I connected some temporary wires for manual starting, so I could decide how to restore the ignition system. I want a separate pushbutton starter, as well as a dedicated power line to an inverter, so I can plug in my computer, tools, cell phone, etc. without having to use the cigarette lighter, etc.
I'll check out the wiring tomorrow, and will be very happy if those are indeed the ignition/starter wires.