Lucas contracts for WD parts supply generally resulted in head-lamps, tail-lamps, voltage control units, etc, all finished in the appropriate WD colour of the period.........so early war khaki-green up to 1942......SCC No.2 brown 42 - 44, and OD after that............as a volume producer, Lucas would likely have followed the colour changes and usage of existing paint stocks reasonably accurately ..........
I wouldn't bother, it would want that much fiddling with that you'd get fed up of cutting the wire and trying to replicate the lead seal!!
Not so much that they were unreliable in daily usage, in fact they are pretty reliable, but they tend to get condensation on the points and need a clean up every now and again if not used all the time
Thank goodness, I don't have to re-paint mine. I had to re-wire the bike with that correct wiring with little color sleeves because of reading this forum!