As gatorcpa said. Movement is most likely genuine and could have been an orphan movement (was in a gold case that was scrapped in the early 80's when gold prices spiked)
Somebody had a new case made for it.
You would need to remove the back to see if any other information is inside
It could also be genuine. Maybe movements imported and cased in Vienna to avoid taxes on gold watches. Looks like a quality made case and similar in design to some other Omega cases
DON