Please consider donating to help offset our high running costs.

As I see it, your only hope would be to try to pin down the identification of the subject watch using the numbers at the bottom of the dial below the 6, to try to pick up a donor watch with (hopefully) a useable movement. Forget trying to fit a mechanical, self-wind movement to the case. An auto wind movement would be about twice as thick, so no room in the case.
And this was what a CK2998 went for in the early days:
https://omegaforums.net/threads/fs-omega-2998-6-good-cond-working-perf.1225/
The bracelet clasp on my 1970s Casio also broke and I lost the watch.
As it happened on the only occasion that I was in a trapeze harness and the racing dinghy had capsized in the English Channel, I didn’t worry to much but I can still picture it floating off my wrist (we were both under water) and I was concentrating on getting under the buoyed hull (I’d seen 'The Poseidon Adventure') where I was able to unclip the entangled harness.
I never went back for the watch, or near a racing dingy again 😀
My little sister was sitting on my couch trying to watch something and looking for the remote down the side of the cushion, she found a 16610 submariner in a plastic zip lock bag, pulled it out and goes “is this… a Rolex?”. I didn’t remember ever owning a 16610 but eventually figured out I’d taken it on trade for a Speedmaster 321 several years earlier and fallen asleep on the couch after doing the deal and having some drinks.
Not (yet) lost a watch, but regularly forget that I have these "side collections" of Swatches and Soviet watches that I don't think about so often. I really should streamline the collection. But it's so nice to have a Raketa Komandirskie and Copernicus. And those others.. damn.