Dave Weimer has
One 90 min. cassette labeled only "Pittsburgh 4/6/78"
Article in Pittsburgh Post-Gazette
Printed April 1, 1978 - the week before
Also in Google News
Richard Rose, author of the Albigen Papers, a manuscript on Zen Esoteric Philosophy, will speak Thursday at 7:30 p.m. in the first floor dining room of the University of Pittsburgh student union in Oakland. The talk and dialog will be on the topic "Zen: The Most Perfect Psychoanalysis". It is sponsored by the Esoteric Studies Society, a group of Pitt Students.
This is the same date as 1978-0406-Group-Meeting-Pittsburgh which is not a group meeting
Have to start transcribing this to see where it fits.