Rocket J Squirrel here, with a message to all:
D'oh!
Nice sunny day today so climbed under the Wonderbus to ascertain condition transmission-ground strap in preparation to possibly jumping bus to find intermittent electrical problem (thanks, Jim, nice to see you over in sci.electronics.*).
Condition good.
Peer into engine room and . . . lookee there: the wire from the alternator (Brazilian 1776 engine, not original 71 engine) had come loose from the crimp sleeve, so the alternator was not charging battery. BTW, the wire which had come out of the sleeve was not touching anything.
I guess that pretty much explains:
A. Glowing GEN lamps, and B. Fading battery two nights ago in the dark with headlamps getting dimmer and dimmer.
BUT (wait for it) I don't think that a bad or intermittent connection explain the other symptoms, e.g.,
C. Tach going inaccurate: reading high, and getting spastic with upward spikes, D. Engine just dying with clutch in while drifting into driveway, E. Starter not even wanting to turn that engine over, but F. Turning it over just fine 15 minutes later.
I'm heading out on a little errand cruise to see how she handles. I've got a life vest, signal flares, rope ladder, emergency whistle, handy-talkie, first aid kit with splints and epinephrine stick, screwdriver, vice grips, welding iron, GPS, poison oak cream, water purification tablets and sun hat. Pretty much ready for anything.