The Technirama process does work better with a 2.35 aspect ratio. A 2.55 to 1 AR would have to be vertically cropped. I hope that at least one of the two collectors (if they indeed have multichannel magnetic sound on those prints) will get in contact with MGM.
Checking a Blu-Ray release against an available IBTech print might already be considered too costly for some titles, but hopefully not for The Big Country.