You should have +12V to the black wire at the coil with ignition ON. The green wire is switched (Which also feeds rev counter) So does the rev counter move do anything when you turn it over?

It's not uncommon on RST'S for the green wire to break, so check this for continuity, thirdly I believe the RST uses a Transistor based module on the dizzy for the ignition timing, I may be wrong but if it does it will be fixed to the outer body of the dizzy with it's associated connector, these are known for failure.

Martin