Hmmmmm...
I'd say avoid using any 1680 case as the dial for a 1680 measures 26.5; a 9411 dial measures 26mm. With a 26.5mm aperture, the dial will likely not have enough case lip to seat against.
For movement, go with a 2783 or 2784 if you can find one. The 2784 is what the gen uses, and will allow you to use the dial without cutting dial feet. The datewheel also lines up perfect. The 2783 is the same except in lower beat rate. Still usable, in my opinion and you can sometimes find these cheap. I used to pick them up for $20 a piece
Wish I would have known you were going to do one of these! I just gave away a gen 25-125 crystal!
Doh!