I have no idea what ref or movement. Don't even know what size it is.
The swirled/twisted lugs and apparently untouched condition made me throw in a bid.
It should be heading this way soon. In the meantime it could be cool to see if anyone out there manages to identify it.

 

looks like a 2639 on the caseback

 

Wrong lug design. It's those swirled/twisted lugs that I don't see too often.

 

Dont agre here are some of mine 2639 and they have twisted lugs

 

Only looked at the Omega photo.
Fully agree that your looks the same.
Thanks!!

 

And the back is the same

 

So, it arrived, and I am rather pleased with it.
Only a light cleaning so far, and I like it. The crystal is signed, but have some light cracks at one side. Could be original, so I think I will keep it "as is".
35.5mm diameter. Signed crown. Dial has some light aging, but all within reason. Cal 265 movement is keeping time over 24 hours. Ref is 2639-1. @tdn-dk was spot on!