Thanks for the link and the offer, Gordon. The most basic flash I have is a small Vivitar thyristor flash with a single contact. Every camera I have triggers it, including my Canonet 28. Since the camera already has a "hot shoe", do I still need the adaptor? I wonder if the hotshoe is electrically connected to anything. Seems dead to me.
I sold some of these new back in the day. Good and capable cameras, but not a path I cared to follow. Unless there is some family / sentimental attachment, or a hoard of lenses, I would suggest either Canon or Nikon of the period which can be acquired affordably, and based on experience were more advanced.