what about the bulb?
I just went to the local AutoZone store and looked at their selection of lightbulbs. They had quite a few BA9 type bulbs .....
some had large glass domes that exceeded 9mm in diameter, some had small spherical bulbs that were the same diameter as the base, and the one I picked had a 9mm diameter tubular glass dome, was rated at 14 volts, and the wattage was higher than the small spherical bulbs.
Whereas the bulbs with the BA9 base and the larger glass domes won't fit in through the bushing for the pilot lamp, the tubular style fits well, and, sticks out into the pre-focus area.
the 14 volt bulbs look a little yellow-ish compared to a 12 volt bulb - but they will last longer and *I* think the warmer light looks "correct" for the classic style. reminiscent of an older 6-volt system.