Comment by dado3212
Did a similar deep dive for one of the posters for the cult classic movie Possession (1981). Just giving random phone numbers a call is incredibly effective, lots of people are happy to reminisce about old work and have great stories.
Very often these people are so humble and so amazed to find that anyone cares so much about some little project they did. I've brought some people to comic cons and they have been blown away by the fans they never knew they had. (and they always have fascinating industry stories to tell)