The 7R was only ever a pure road racing bike. It was only built for one purpose and that is what your father is doing with it in the photo. It was a single overhead camshaft, single cylinder road race bike of 350cc and its common nickname was "Boy Racer". As everyone would carry out little 'tweaks' to get a fraction more power I'm not surprised the exhaust pipe isn't exactly as the bike came from the factory. Both the factory and owners were constantly updating and improving things so don't ever expect to see a standard catalogue 7R on the race track.
Cheers,