yeah, you're experiencing the perennial "my handlebar bag is interfering with the cockpit functionality" touring quandry. you'll wind up recabling, adding a second stem, etc....
heavy film SLRs like a pentax k1000 with lenses are usually stowed in better places than a handlebar bag. but for load carrying up high and in front, a rack supported front bag is the way to go. Berthoud, Ostrich bags, or just rig a trad, padded back rack bag on top of a decked front rack.