I use Testor's glosscoat first, then apply the decal (the glosscoat hides the decal film), then dust on Testor's Dullcoat. This works well on Revellogram vinyl tires (Nascars and the old Blue Streak big and little tire sets)
RCS Motorsport Models of Texas
I've had a Petty conversion of the Revell Superbird "in progress" for several years now. Biggist issue I had was sanding the vinyl roof off of it. The Petty decals included in one release of the kit (street version with Petty decals on it) are actually those he ran at the mid year Riverside 400 road race.
If they aren't too bad I'd try using Testors liquid glue to fill it in. Brush a little on let it dry, apply again until you get it built up. Then sand it smooth. This is an old airplane builder trick to hide the seams when you put a fuselage together.
Here's mine. I have to paint in my garage on my workbench. I just finished laying down the paint job of my life. It was perfect. Then a Junebug flies into my overhead light and knocks a bunch of dust down onto that fresh wet paint. Still haven't gotten over it.......