I would do a 75 750 F...
Im not an expert, and this is the only "f" model i have had (others were k), but I think the lines would work out well for you. The narrower tank, the shapier seat, the style of the rear fender ect. Check out glenn's cafe thats for sale, might give you some ideas and i think an F model will allow you to make minimal changes and still come up with a good lookin ride.