Wow, you're goin' back indeed. The Folklore Center was run by Izzy Young, and may have been taken over by Marc after Izzy ran off to Sweden, to start the same kind of store there. I did a concert in Toronto a couple of years ago with Stefan Grossman and John Renbourne, and to the best of my knowledge Stefan is still involved with recording, teaching videos, and touring. Best recording of "Tell Ol Bill" I've heard was by Dave Van Ronk on Folkways. But I'll bet it's the Henske one you remember.