This is not a Surf King. 11AFC sweep seconds movement, 33mm diamater steel case, 9mm thick including the crystal. I'm going to have this one serviced. I can't find a model designation.
This one has me stumped. My first thought was that it was a model produced in Europe or "International"; however, the movement bears a 3 letter import stamp, meaning the movement came to the US without a casing. European produced watches don't have the US import stamping .
The case is marked "Swiss" but isn't stamped "Bulova". The markings are puzzling, as it has a "MO" date stamp inside back, as well as what appears to be a tiny M2 on the outside under the stamped number. It also seems to have 2 different potential serial numbers, one inside and one outside. I suspect the casing and maybe the face as well are aftermarket; meaning the Bulova movement was installed in a replacement case made by someone else.
Pending further research, my thought at this point is
1961 Non-conforming (dating by Bulova movement date code)
Non-conforming is how we designate a watch that isn't all Bulova parts that doesn't correspond to any known model.
'MO' is either a date code or the casemaker, but not seeing any match for this.
I have seen this before, the case is clearly Swiss and carries a distinctly Bulova date code, at least on the outside, which appears to be M2.
We've seen Swiss cased Bulovas that only carry the casemaker's mark before, this may be what this is. The presence of the import code may mean that the watch was imported to the US, despite being cased in Europe.
I'm at unknown.