Tonymorr is going to nail it with the Ninja 300 conversion. The engine is a doll of a motor. The torque is flat and useable, the gears are spread wide enough for one sprocket set to do trails and highway. Capable of big MPH numbers and smooth at high RPMs.
I rode/raced KTM Adv and/or a SE950 since 2003. Put this 300cc engine in a SE type frame and it would be a riot. In an Adv it would put the KLR out of business. No, it won't power wheelie in 3rd gear, but it would be nimble off road and do over 100 MPH.
Kawasaki needs to hire a few guys away from KTM and grow a set!