Watch looks ok - some patina on the dial but otherwise in good shape.

 

It looks legit to me. I think the dial was redone at some point. It's a rather unusual case reference. Not too many of these around.

Only able to find this one:

http://omegaphilia.blogspot.com/2009/04/omega-seamaser-calender-convex-dial.html

Hope this helps,
gatorcpa

 

Looked redialed to me as well. Seamaster font looks off, and there are only 3 minute marks between 11-12 and 12-1 markers.

 

I think it is original. There should be only 3 markers as the 12 is a double piece.

 

Yeah...I took a look at my 2887 and it only has 3 too. I think what was throwing me off was the space between "Seamaster" and "Calendar". Usually I am used to seeing more of a gap:



But then I found this one which looks like the OP's: