They look pretty cool stock...
The squared-off design of the stock tank and body work might be tough to rework into a new look, so I'd accentuate the positive. I'd try lower bars, rearsets and a new gauge of some sort. Acewell, Trailtech, Baja Designs, etc. Maybe a round headlight or trimmer rectangular unit would tidy up the front end. I'd lose the rear fender. Maybe shorten & slim the front...
Nice score. Should be fun no matter what ya do.
Couple Airhead BMWs
Couple Chinese Pitbikes