All 35mm anamorphic projector lenses (and lens and adapter combos) can be rotated 90 degrees in the projector. You could test your idea by shooting with an anamorphic lens mounted at 90 degrees in the camera (you might need a lens tech to fiddle with the lens). It wouldn't be 1:2.4 (by a 3:4 factor assuming academy projector aperture) but it certainly would be a cheap way of testing since it would all be standard gear.
I didn't even think of projector fiddling. What if prints were 1-perf and did the de-squeeze vertically as you've implied? A 2 hour feature could fit on one and a half reels. That could cut the costs of print production to one fourth as well as the costs of shipping. The sound is all going DTS anyway. 2-perf would de-squeeze to Academy frame and wouldn't be of much use. A lot of these newer projectors like the Christies are toothed belt driven. It would be an easy change over to new toothed pulleys. I guess the geneva mechanism would be the biggest change over issue. That and the lens lengths would have to be changed out to make the image fit into the existing screen distances. Asking theaters to move the projectors closer might be too much to ask.
Well... then there's that sucky picture quality issue. Dang. Ideas always start out good.