Here's my number one choice for obscure play:
When I was recording Drat! The Cat! I went to Miss Elaine Stritch's apartment to meet her and rehearse her number. I found her delightful, but that's another story. At one point I told her that I knew it would probably be an unpleasant subject, but that I'd seen and loved Time of the Barracudas in its one and only engagement, the tryout in Los Angeles. She hadn't thought about it in twenty or more years and she started telling stories about it - those stories, of course, ended up in Elaine Stritch at Liberty. In any case, Time of the Barracudas was a play by Brit Peter Barnes (who would go on to write The Ruling Class). It's about two people whose spouses have just died, who meet at the funeral of one of them. It transpires that they are both professional murderers who do in their spouses. They, however, do not know this, and they marry. They spend the rest of the show trying to do each other in. The first act curtain, where the man realizes what's going on, had a wonderful curtain line I've never forgotten: "Good God, a competitor!" Lots of great comedy business in the second act (at a chalet, where they're vacationing). It was a very black comedy and totally ahead of its time, but I've often thought about trying to do a production somewhere. Starring opposite Miss Stritch was Laurence Harvey - they were great the day I saw them. In the early eighties I found the script to the show at some funky shop that had movie memorabilia and some theater stuff. I treasured it, and then, somehow, it went missing. I've looked through every box in my storage facility, but there is one missing box, which has a lot of rare scripts in it. For a time I stored some things in the old Bay Cities offices and some of that got moved to somone's garage - I retrieved all that stuff, but it is my belief that that box is still there, although I went and looked for it and didn't find it. That said, I still think it's buried there somewhere.