UPDATE - I finally have everything working like I want to (no excess light coming through the tach lens). I found that using paint to darken the lens and eliminate the light bleed through didn't work as well as I wanted. The paint didn't adhere to the lens surface very well and covered the lens really unevenly - even with multiple coats of paint). As a result, I went really low tech and used electrical tape which I then trimmed with an exacto knife. IMO, it turned out really well (the light bled through is gone). In addition, I made sure both the tach and clock have the proper light bulbs.
The tach uses a 1895 bulb and the clock uses a 1816 bulb. Not only do the 2 bulb have different brightness levels (1895=2, 1816=3 MSCD*) but their shapes are different as well which is the major reason for using both types of bulbs. The 1895 is a globe shaped bulb (used the dashboard lights and glove box light) whereas the 1816 is a tubular shape so that the filament is placed further down in the holder to get the light where it needs to be. Using these bulbs will make the clock and tach the illuminate with same greenish color and brightness as the rest of the instrument panel.
In addition, I was able to get the clock working again too. Fortunately there was nothing mechanically or electrically wrong with the clock. It just needed to be cleaned and oiled. Once I was able to get it working again I then found out how to fine tune the clock (as it was running a bit fast). There is a lever which controls the spring tension for the clock balance wheel (this is what the winding the clock spring activates). After some adjustments and letting the clock run using a test rig it is now keeping time extremely well. I also learned an important sidenote. The act of adjusting the time on the clock (using the adjuster dial) actually fine tunes the clock speed. As a result, you have to be careful not to adjust the clock too much at once or it will no longer keep time accurately.
Finally the #1 cause of failure in these clocks is a near dead battery which doesn't have any enough power to kick open the winding mechanism and keeps the "points-like winding mechanism closed" which then overheats and burns out the copper windings on the spring actuator (which winds the clock).
So in short, the Rally Pac now looks and functions exactly as it did back in '65. :-). The tach still produces a whiter light as the diffuser is a light redirection lens with a blue strip of plastic on it. The clock is now brighter and blends in nicely with the brightness of the dashboard lights.
*MSCD - ["Mean Spherical Candela", or "candlepower"]
Regards,
Ron
