It is approx 4.30 ~ 5.00 hrs drive (am not sure about bikes speed). There is no Charhai and CD70 should rock.
One can reach Mangle via GT Road and you need to take a right turn after Jehlum. The exact point is in between Jehlum and Dina.
Their is a water sports club at Mangla and you can go for boating ans water scooting. On the way back you can got to Rohtas Fort on the GT road (few kilometers off).
The best would be to use Google Maps