A former Imagineer chimes in:
As to the stunt show, this was developed under the Entertainment department on their own rather than Imagineering which was probably why it was not well known. An outside consultant was brought in and I seem to remember a model might also have been done. It was essentially a comic gun fight with exploding buildings and such but, as Jeff said, it was cancelled because of the clash with the Buffalo Bill show.
I always like reading about theme park attractions that never were.