Paint line between interior and exterior color?

Can you post photos as I’m trying to picture what the problem is?

On ‘73 and later plastic uppers on the doors and door card/panels covered everything below. So the doors are sprayed body colour but then covered by plastic and door cards so you don’t actually see paint on the interior of the doors when sitting inside. Same with the back seat area and kick panels in the front seat area. The dash was painted but it’s not beside any other painted surface.
If it is a Dart Sport (aka Demon) yes it had the new interior with plastic or other materials covering everything. If it was a Dart Swinger (old body style) there was still metal showing in the interior.