LED's would be a good choice for some lamps, but the biggest problem is that they don't dim. If they are too bright, not much you can do. The factory dimmer added resistance to the filaments, which would make them pretty dim, but LED's are either on or off so adding resistance has no real effect on the intensity.
You have to PWM an LED to effectively dim it. If you want to get creative, you can use these on the dash LED's to dim them inexpensively:
https://www.ebay.com/itm/12V-RF-Wir...610433?hash=item3aaed9c4c1:g:x74AAOSwgQ9VuXin