IIRC 48-50 at the real wheel is par for the course on a Class B bike.
Dynos can vary a bit though and there are a lot of things that can affect the real wheel horsepower other than how good the engine is.
Was the dyno operator happy that is as good as the engine can manage. Did they give any feedback on the fuelling?
You'll find out for sure if you are down on HP on the long journery to the first corner.
Ray