interior plastic color change

Yes you can change the color of the plastic and also the vinyl interior parts.
The hard plastic stuff can be painted.
For Vinyl there is special paints with some flexibility and also dyes. I've used SEM products (Landau black is an almost perfect match for my '66 Valiant), Eastwood has some prodcuts and Dupli-Color has some too.
As mentioned the important thing is to thoroughly clean everything. I used Simple Green, when the water doesn't beed up you've removed all of the Armor All and stuff like that so the new color can stick.