Though not the crispest images, they document the Illuminatus! Seattle production in all its chaotic grandeur.
As I learned from Iona, the Seattle stage production took place at The Empty Space Uncommon Theatre in 1978. At this link is a listing of The Empty Space Uncommon Theatre productions for 1978/79, listing Illuminatus! in three parts. Also listed were a couple other Ken Campbell productions with such interesting titles as Skungpoomery and Psychosis Unclassified.
In the promotion poster below, British Sci-Fi author Brian Aldis had this to say about the Illuminatus! play:
“Nobody is going to believe this… I can’t recall ever sitting in a theatre sweating with suspense while laughing my head off…. here is Genius with a Gee!”