Hello.
I would appreciate some help analysing this watch.

The case serial doesn't match the movement serial, but it is a Longines - Wittnauer case.
Longines bought Wittnauer in 1950, & the 23zs seems to be a 1950's movement.
Does LXW on the movt. mean Longines Wittnauer?
I have searched the net for pictures, & found no other cases like this one.
I find the watch very attractive.
Here is the dial:

Thank you for your help.

 

I am not familiar with the model, but see no reason to believe that it is other than original.

 

Thanks Tony.
I should add the 2 missing screws is a red light for me. I don't understand why they should be missing if somebody hasn't stuffed it around.

 

Yes, but I suspect that is more likely a (bad) maintenance issue, rather than a sign of a "Frankenwatch".

 

I had a couple of perfectly correct manual Longines from the 50s and 60s with missing screws like that... What @Tony C. says is probably true: shoddy "servicing" in its history

 

I have several watches with "missing" case screws and clamps. In those, the movement is held into place by other means - this couldn't be the case here?

 

I haven't held the watch, so it may be as you say.
The crown doesn't look signed, & looks ill fitting in the movt shot. I wondered if this was a sign of a loose movt, but may just be an ill fitted stem/crown.

 

The watch is correct
No missing screws, the movement is held by the fastening ring

 

I didn't win the auction, but I learned a lot in the process.
It went for $300 Aussie, plus $50 shipping.
I wasn't prepared to spend that much on a risky dial.