Wow, cant believe this thread has been dead for almost a year. Time to update it......
@Anchorhead,
Practically any theater back in the day could show a movie in scope, providing they had the proper lenses and aperture plates for the format. Theater size has nothing to do with it. Also if the image spills onto the curtains then the aperture plate was not cut right to fit the screen. A common problem still for cinemas today. As far as the cropping goes, ( again ) it's mainly due to an improperly cut aperture plate, and most theater chains don't care much about that to fix it, especially if the theater is not getting any complaints.