Okay, wonderful advisors, as the sun sets on another unproductive day I give you the results of my efforts.
I cleaned up the coil-bracket grounds and the spade connectors for the ignition amp. There's now power at the coil negative terminal. The coil wire leading to the distributor doesn't spark at all when I turn it over, no juice there whatever. A new coil makes no difference. During all this, the ignition relay under-dash clicks as the engine turns over. If I turn the key almost but not quite to start, I hear the fuel-pump whine, and the ignition relay starts clicking.
I checked the ECU wires for loose connections, everything's tight. I ran down to the junkyard and pulled another relay - no change with the new one, I should have guessed but had to try.
My choices now, as I see it, are maybe still the ignition amp (the junkyard didn't have one), the distributor, or (gulp) the ECU.
Any thoughts? Any way I can check these things to narrow it further? Thanks much.
Tony B