Hi,
I think it is a model 800. The serial of the case dates it from around 1929. Omega had production serial numbers for their calibers and for the cases so watches before the 50's didn't have matching numbers for both. The production year of the caliber could be earlier than the case but it is not abnormal, they used to produce batches of movements and put them in cases later, taking from the stocks on a need basis.
Nice enamel dial with Breguet hands in what seems to be very good condition. The caliber is a 26.5 SOB, the first design before 26.5 SOB T1 (T1 stands for transformation n°1). I'm not a watchmaker but the caliber looks dirty and would need a good cleaning, oiling and timing.
Here is ref 800 (with a radium dial) in a 1927 catalog :
Here in a 1930 Catalog (same dial and hands as yours) :
Here in a 1933 catalog, different dial with raised numerals, and unusual strap :
Mine says hello :
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