close up picture of Mk1 Speedometer required

[Lynn Eades]

If you had a Mk I* speedo (see attached picture) I think they are completely safe. My guess is that they relied entirely on the panel light
I dont think there is any "luminous" stuff in there. Maybe the radium paint in the MkII* is the result of comlpaints about not being able to see the MkI* speedo at night.
With your MkII*, maybe it would be better to buy a nos one, and dispose of the old one. What ever you do, be careful.