It's fine, I can wait. Harmy's comparison already shows that the Senator screening was at about 2.20:1 instead of 2.35:1-2.40:1, so I think my estimate is close enough for now.

I worked on a new chart to approximate theatrical cropping in '77 - this is the binary sunset scene. The boxes roughly represent full aperture, 5% cropping and 10% cropping. I'm not well-versed in things like aperture plates and masking, I'm just drawing boxes on an SMPTE framing chart and trying to match the boxes to the dimensions of the frame.

I've read that there was usually some masking around the edges with Panavision, if only to cover the flashes at the splice marks. And obviously, any video transfer would crop off at least a little bit, to remove the soft, rounded edges.

A simple way to think of it is, the vaporator on the right was probably visible in a majority of theaters in '77. :)