Talked to the knowledgeable and generous Scott of Turbovans, and he said "look for bad grounds in the starter circuit" and lo & behold, there was a short in the starter ground. Screw had backed out. I removed the surface grunge with emery, and used a tiny bit of loc-tite blue on the screw. 
And off I go to Bainbridge Island. 

But - I'd still like to buy a spare ig switch. Since Cunegonde needs to be re-keyed anyway, anyone have a used one?

Bretts

83.5 Ivory 1.9l WBX "Cunegonde"