Here is my thoughts. Not ready for exterior paint yet (still working on the mechanical side of things) but the interior is gutted. The PO had shot the exterior with a really bad paint job (which will need to be removed later) with lots of overspray onto the dash and interior doors. For now, I would like to sand down the interior (overspray on dash and paint brush applied bed liner material around windows) and complete some of the repairs, then shoot it with rustoleum primer(sandable) and a top coat of rustoleum dark grey paint. This will let me install the interior for now. Down the road, once I have decided on a color, I will remove the interior and windows and have the truck interior painted the same as the exterior.

My question....Can you shoot a sealer or something over the rustoleum which will allow the application of a single stage urethane later?