Hi Spanner, I too have been a long time looking for a 120 mph chronometric speedo (revulator?), but for a 1957 Triumph Speed Twin. The 5T speedo dial is marked S467/99/L. There seem to be so many variants, and there must be a good reason. Maybe some are a different diameter or fitting, or perhaps the rotation speed of the drive cable is not always the same. Or it may be the rev. limits on the dial etc.
If AJAYTIBSY does not take you up on this and you think it might be suitable for me, please get in touch. My email is jamesrambler@hotmail.co.uk .
Jim Walker