The green stuff is basically just to filter the light from regular globes to make it green coloured. It's on the back side of the black guage faces (Thin piece of plastic with the dials/numbers on it)
So this is what I sandpapered off, and replaced with a coat of modelling paint. You could probably also use cellophane.
The LEDs are different - because I repainted the needles white, they became very dim at night, so I put LEDs underneath the base of them to compensate. (Stock needles must have some special stuff on them which reacts to light much better than paint).
I don't know much/anything about the U13 dash. but I'd imagine that, being from Nissan and being of a similar vintage (Only one revision up), I'd think it would be the same/similar.