does anybody remember who was building generic front panels

[Tom Jennings]

>> Has anybody tried using the white leds for displays?
>
> Have not checked those. Also (in The Netherlands) they cost
> more than the orange/yellowish ones.

But LEDs are sooooo unlike incandescent lamps! Your brain will
know immediately. I mean to experiment with an RC network on a
grounded-emitter driver for the LED to get closer to filament
behavior, but the color will be much harder. Likely it varies with
temp, but you might get "close enough" with a simple filter;
especially if you can put a little nick in the back of the filter
to make the little filamentary bright spot.  You notice that
filament, you just don't notice that you notice.

(Period technical aesthetic "forgery" is kind of a specialty of
mine...  :-)