I also have a set of those same BS34s. You will notice that the mixture screw is different from XS650 mixture screws. In your picture, you can see -- the XS650 screw is stepped, while the other screw is tapered. The hole in the carb body is also different, so they won't interchange. I have no idea what bike those carbs are off of, could be any of dozens Suzukis or Kawasakis.
Makes me further wonder about the EPA requirement to plug the mix hole access on 1980 and later XS650s, because I think the those BS34s in your pic are from the same time, and they are not plugged.