Hi Webtechy,
Welcome to the wonderful world of the Classic.
When you take the Binnacle cover off, pop outside and look at the back of the speedo cluster.
You will see all the bulbs and bayonet holders, Do this at night with your inginition and lights on and you will see the ones not alight.
(About 15 lamps)
When you go to get spare lamps take a sample with you and compare the replacement carefully with yours, I have found a lot of similar bulbs but they don't fit.
If the optic lamps have gone I think they are under the gear lever panel.
Good Luck