by which I mean the aspect ratio it was intended to be viewed in.
For example, Gone with the Wind is
11:8, or 1.375:1. Indeed, the reason for 4:3 is that back in the day, 11:8 (which is approximately 4:3, or 1.333...:1) was
the normal aspect ratio for theatrical films [see http://en.wikipedia.org/wiki/Academy_ratio
]. Today, it's normally wider, of course.