One other thing ....
The early DR 650s had a PAPER cylinder gasket, which was prone to leaks and lower compression problems. You might want to check your compression as well. You should probably upgrade with a new metal gasket before you take off on any long trips.
Other than these issue, just add a bigger tank, a bit of a wind screen, some decent tires, and ?perhaps a smaller front sprocket?.
The DR 650 is one of my favorite dual sport rides for short trips and lots of dirt. For longer rides, or more hiway oriented travel, I prefer the improved comfort, smoothness and power of the DL 650.