Rog, not sure if you can visuallize this but. If you look at the picture you sent, take the current position of section the gear linkage that bolts to the gear shaft. Now put a bend in it and extend it backwards and under the engine. Run a linkage bar from this behind the frame section wher the chanin would normally run, since there isnt a chain on this side there should be room. Take the existing lever, instead of pivoting on the hanger, remove the pivot and drill through the hanger so it can take a shaft, attach the shaft to the gear leaver and a suitable level at the other end and then attach the linkage bar.
Did that make sense ?