Hi Graham,

Yes this can be achieved. I use a MIDITECH MT-61 controller as a lower keyboard and a MIDI pedal board so that the KN7000 effectively becomes a full organ with 2 x 61 note keyboards and a 13 note pedal board. MIDI outputs from the MT-61 and Pedal board are combined in MIDIMAN 2x2 merge unit and fed into the KN7000.
You can use the split function in the the manner you described to set the upper keyboard to play only the R1 and R2 parts. Then by selecting Program Menus, MIDI and Part Setting on the KN7000 you can assign the left hand part and chords to the MIDI channel corresponding to the lower keyboard. You can also use the octave setting to optimise the range of the lower keyboard.

Hope this is of some assistance.

Cheers
Len C.