Since 78_targa implicated me in the alarm delete evildoing, I figure I'll post the update on how we solved it this morning.
It stood to reason that we screwed something up on the alarm delete, so we started with a focus on the ignition system. Following the Bentley manual, we tested for voltage at terminal 15 of the CDS -- it showed a healthy 12.4VDC. We plugged the CDS connector back in and decided to check things the old fashioned way. We pulled the center wire off the distributor cap, held the tip of it about 1/4" away from the fan shroud, and cranked the engine -- to our surprise, we actually had spark.
We screwed around re-reading ignition system diagnostics for a while, to no avail. For as much as we had cranked the engine, it just didn't smell as gassy in the garage as I would expect, so we turned our focus to the fuel system.
Again following the Bentley manual, we pulled the airbox cover and filter, and manually lifted up on the air flow sensor -- doing this with the ignition turned to 'run' triggers the fuel pump relay. We could hear the relay clicking on and off, but we didn't hear the fuel pump running.
AHA! Surely we must have missed an alarm cutoff relay for the fuel pump, we thought. Or maybe 78_targa has the world's quietest fuel pump.
We dropped the belly pan, and check for voltage at the fuel pump terminals while lifting the air flow sensor. No voltage there, so we traced the wires back up into the trunk. We didn't spot any extraneous relays, so I thought I'd at least confirm which relay was clicking. I put my hands on all 3 relays in the fuse panel, while we lifted the air flow sensor again, to see which relay clicked. When the air flow sensor was lifted, I saw a slight spark inside the casing of the fuel pump relay (colored red in this car, and located at the rear of the fuse panel), and suddenly...
The fuel pump took off! And it wasn't the world's quietest, not by a long shot.
Turns out, in all of my screwing around during the alarm delete, I had physically dislodged the fuel pump relay, just ever so slightly. We seated the relay fully, and the car started and ran beautifully.
So, in the end, it's still my fault, but I feel somewhat exonerated that it at least wasn't a bungled (un)wiring job.
Cheers,