Timing is everything
Today I re-installed the thermostat housing, alternator, and distributor in the Mustang. That was a cozy 30 minutes. I was feeling confident so I decided to check the ignition timing.
I had everything hooked up (battery / remote starter switch / timing light) and the ignition key-switch turned on. Cranked the engine over about 15 second and there was no flashing from the timing light.
I bought this timing light "about" 1982 for my dad, because I had mangled his seriously professional model in a bizarre fan entanglement incident. It was the best that I could afford and I remember paying dearly - $26 - at the Montgomery Ward auto department for this imported plastic model. Dad gave it back to me when I moved across country. I'm pretty sure all of his cars were computer controlled by that time.
It worked the last time I used it, but I'm thinking now that was around 2009. I gently opened the case and found that (like a lot of my tools) either it got left out in the weather, or this capacitor got carsick all over the circuit board.

This lead me to an hour-long shopping search ,both local and shipped. It seems that I can still buy a timing light for $26 up to $250. The reviewers aren't kind on any of them. A common theme is they work once and then something breaks and they stop working.
I was half dozing when I remembered that I bought a briefcase with some automotive tools at a thrift store.
Several Years and one move ago.
It's a good thing I remembered where I stored it.
Jackpot!
Not one, but 2 timing lights. also 1 compression gage, a dwell / tach / points angle meter, and other accumulated dross.
It seems the Sun light has a recessed switch trigger that's a little too recessed.

Let's fing out why:

a simple momentary spring-loaded trigger switch. The plastic outer case broke and the spring self-unloaded.
My solution:

hey - there's a spring in an aligator clip. and the pigtail can be yanked in case of smoke, sparks, or other non-commital concerns.
It worked! and the timing was pretty close, with plug #1 sparking in the neighborhood of TDC.