I am not sure whether the B707 ever did not have hydraulic boost to the rudder system or not.
According to 'Cats Eyes' Cunningham (I think) in his auto-biography, Boeing only fitted the rudder boost as a consequence of his insistance (to the UK CAA) that an average pilot would not-in certain conditions-be able to control the a/c. I think he meant after an engine failure at T/O, but as i don't have the book anymore I can't check. I'm sure someone will.