And the culprit was ...... bad ignition switch.
The original harness connector between the ignition switch and the fuse box harness was long gone of course, all of the wires were connected with butt connectors. The butt connector for the black wire was pretty crispy, it had obvisouly been pretty hot sometime in the past. The windshield wiper motor only runs for a little while before it overheats and stops, I suspect that it may be the cause of the cooked wire. Anyhow, I think the ignition switch must have gotten a little cooked as well and was shorting out the ground on the column when the key was turned on.
A new ignition switch and a couple hours of wiring cleanup under the dash and everything seems to work.
One final question - on the column, what is the little black button in front of the hazard switch for? In dismantling the column I broke its mount.
