I am about to have my truck painted and the wheel moldings I have now could definitely need replaced too as where the screws went through the metal is corroded and eaten away. I’m having trouble finding the correct sizes online as most of them won’t cover the whole area like the ones I currently own. Any help would be appreciated!

side note- also looking for the side molding that would go around the truck (8’ bed) as the black is well worn and the chrome tape looks awful. It looks like this style might have been discontinued.? Thank you!

 

There is a 86/87 parts manual in the FAQ section about halfway down. Having the part number may assist your search.
There are some online databases for used parts too.