Hi Cap (and Welcome to the Forum),
I'll answer your PM here so we all can share.
If it was the gearbox, or back towards the wheel, I think it would not be so specific to one rev point.
Out of interest, I took my 750 to 6000 in 3rd gear (first time past 5000 !) and heard nothing of interest.
My bike is very new, how many has yours done and what year?
Just thinking aloud is it age related or something obscure like a dry chain that needs to be replaced or a front brake caliper dragging issue.
I am sure you have discounted air whistles from your helmet visor. I was doing 90 KPH at that rev point.