Final Report:

Weather cooperated enough, i.e. heavy rain washed the salt off the roads, for me to do a nighttime test. I'm really happy. Lighting is perfect brightness, nice green glow allows me to read all instruments perfectly and not too bright to distract my vision. Don't need a dimmer.

Again, used the T10 LEDs noted above, placing them in the original sockets after widening the contacts to accommodate the thicker (not wider) wedge bases, Only odd man was the clock. That used a different type of bulb, so I snipped it off and then cut down the bulb barrel on the back of the clock by 1/4". Using one of the sockets I bought, also detailed above, allowed the LED to bottom in the barrel and the rubber part of the socket to fit snuggly around the outside. The hot pigtail socket wire was grafted onto the snipped red lead and the grounding pigtail got a female spade connector and was attached to the terminal on the back of the clock case.

Probably should have used a smaller LED that actually extended into the clock case, but I can read the clock, though it isn't as bright as the others, so, for now, if it ain't broke...