Bulova 1963 Regatta 23
I'm not sure what model it is. The dial appears to be the same as the President OW from previous years but the lugs are a different shape.
The Bezel is 10K filled.
The non-rotating back is secured with a screw-down ring (not sure when the technical term for this type of back is).
I don't know its history and it is currently not working.