Buy a quart of Slick Sand through your local auto paint supplier or a online place like Eastwood. Slick Sand is a HEAVY primer/filler. Apply as per the tech sheet. Only spray it on the bad areas, then block sand it smooth. This will help to level out the waves. Once its to your liking, prime again with a normal primer or sealer, then your favorite paint.

-Dave-
Collects Dino era Sinclair & Mopar items