Get the right bulbs and they will work fine. Have had them in the fiver tail lights for several years and all 8 lights on the truck are LEDS. They come on faster and brighter than incandescent bulbs.
You might try
these from Iowa80.com
Only issue is sufficient resistance for the directional flasher to operate properly. I have four taillights on the fiver; with 4 LEDs the signals would not operate properly. With LEDs in 2 of them everything works fine and I have the added benefit of the top brake lights (LED) coming on a split second before the lower ones (incandescent bulbs.)
I have red LEDs behind red lenses as that was all I could get at the time. I expect that white LEDs behind red lenses might be a bit brighter.