It was something I looked at some years ago when examining the transmission first. Like flipping the 3rd gear pair to give the 6th gear pair, you can indeed also flip the output helical gear and the torsion damper helical gear and not have any centres challenges.
However my feel at the time was, one would have to get 2 new gears made (the torsion damper one is a bit special as the torsion damper follower has to mate with it), and one would also have to get 2 gears made for the 6th gear too.
Having gone further down the road it became apparent that several more parts were needed for the 6th gear, but still only 2 gears needed for the output/torsion rearrangement.
But the 6th still yielded much much greater results in terms of speed capability and rpm drop for cruising (and let's not forget making use of the 6th gear spot on the detent & shift drum), so onward Christian soldiers we went.
Kind of kept the torsion gear flip as a further enhancement in the back pocket, for when the 6th gear was not quite enough, this could be added on too for extra excess.
Sort of like oversize pistons and custom liners was next, after completing the stroke job.
