I did this for my YZF750 track bike. Easy to do, by simply flipping the splined clamp on the selector shaft. It changes the angle of the linkage arms but has the desired effect of 1-up, 5-down.
You can’t do this on a Fazer1000, because, as you correctly mention, the linkages go through a channel in the frame, and any changes to linkage arm routing cannot be accommodated.
If you do find a way (other than a major mechanical mod), I’d be happy to hear it.