On the gen 3135 hands, the pinion can be broached to make them fit an ETA. I think it would also be possible to do the same to 1575 hands but bear in mind that they won’t be usable for a gen cal anymore after that.
You might as well use a good case for it. I personally am not a fan of plated cases, as no matter what happens, the gold plate will always fade. Sooner or later. This is my old lady. Solid gold case and gen everything else.