Remove the dash, rip all the vinyl and such off of it, clean it, then fiberglass over the entire thing. Follow up with body filler/ lots of sanding and when it's ready then paint. Enjoy your new project that'll take quite a long time.
If you do paint the dash just know your resale ability will drop like crazy if you glass it and do something out of the ordinary. Average person won't want to buy something like that.