Just to close the loop on an earlier posting, I heard back from Castle Hill about the version of Othello referencing its 1992 copyright. As suspected, it's the "restored" version, such as it existed at that time - and since reworked some more by the restoration team, I am led to believe, which accounts for the current DVD edition.
So, folks, it seems it's either the Voyager/Criterion laserdisc (or a bootleg thereof), a visit to the Library of Congress, a lucky find in some film vault or library, somewhere - or nothing when it comes to viewing this work in its earlier (some might say "unmolested") form.
I guess one could say that, in some respects, Orson Welles's Othello is almost as lost today as it ever was. Blessed all the more, then, are those who are working to preserve at least as much of it as they can.