Just looking at some old Curborough twisty sprint photos, I spotted the odd gear lever. I remember on the first run of the day I crashed Don Alexander's racing Comet and broke the gear lever so for the rest of the day I rode the Comet with the lever from my pre-war cammy Norton.
So, levers from the 'doll's head' upright Norton gearbox should fit a Burman box. But cammy Norton parts are like hen's teeth I hear you say........ no, not the gear lever, it's the same spline (sorry Grank Fiffin... serrations) as the millions of WD Nortons.
So there's another option.
Paul.