This one is a little unusual. It is clearly a 1970's Senator but I cannot find this dial in any of the A-F variants. This is a stainless case with an N1 date code and 10K gold fluted bezel ring. The movement is a 23J 11ANACB also with an N1 date code. The dial is sunburst silver with a matte blue minute track. I checked all the linebooks but cannot seem to find a match to this dial. I am fairly certain it is a factory model and might be a variant higher than F if one existed.
I've just added my copy of this watch to support your view that this is an original Bulova model. I share your view that it is most likely to be an International model. The back of my watch, which is identical to the photo of yours, is very much in the style used by the International division of Bulova in the early 1970s. My copy of this watch has a gold coloured crown which fits well with the style of the watch but I've never been confident that it is the original crown colour. The bracelet is not original: I added it when I bought the watch several years ago.
If this is indeed an International model then the "Senator" designation is probably not appropriate.