OK. Finally got repairs to the point I could do a test run with the Zephyr this morning.
At first start it smoked a little bit, drivers side just forward of the firewall, so back up on the lift - I decided there was residual oil under the car, soaked into the heat reduction tape on the collector and elsewhere, so we went for a ride anyway.
Checked the oil pressure gauge lines for leaks and so far, so good.
The new alternator went in with drama (it used a metric bolt instead of the through bolt, the mount needed to be bent to align the brackets, it ended up needing a 1" shorter belt,) but you know it just bolted right in...
The result of the new alternator was just what the doctor ordered: the voltmeter indicated a steady 12.5V for the entire test ride, and (DRUM ROLL) the temperature gauge went to 205 degrees and stayed there! I'm convinced the temperature gauge was trying to tell me the alternator had a problem.
Overall the car seemed quieter, possibly because the engine wasn't resting its header on the steering shaft and maybe other places.
On to the next one I am certain