I see what you are doing mathematically, but it doesn't look right to me. When I went to Cinerama many moons ago, the screen was very much wider than this. The 2001 image looks too tall and not wide enough.
These look closer to the screen dimensions that I remember:
The ones below look too narrow and too tall to me.
There, that did it quite well for this rough rendering. And here is how it would look on your widescreen TV:
