Dont get any DR650 crap. Get an XR650R, never buy again. This is the bike that won the baja 1000 like 10 times. DR650s are nutless compared to an XR650R.
Get one of these, the on road Baja Designs conversion kit, and get some used sumo wheels off of supermotojunkie.com. You'll need a brake conversion kit and a larger stator too I believe.