1974 Dart Swinger

Any Enamel spray would do, Rust-oleum is pretty common and a good product. If you want to get fancy you could scuff pad what's there now, use some high build spray bomb primer (Pep Boys or the like) sand smooth (600 or 1000 grit) then apply the flat or satin black. You can also pick up some sheet plastic at Lowe's or the like and cover the whole car, then cut out the roof and tape the plastic to the edges. This way no over spray gets on the rest of the car.

I remember my aunt had a Toyota Corolla when they first came to the states like in the mid - late 60s and she took it somewhere to have a simulated vinyl roof sprayed on. You could just do the roof with a bed liner textured material, but then when it comes time to strip it off it could be a pain? Not sure how difficult it is to get that stuff off? Probably best to just stick with an enamel paint to spruce it up and give the roof some more protection.

Do share pictures when you get done. I agree the Crager S/S are sweet, on my duster I had the 3-spoke Crager S/S center caps as a unique touch = nobody else had even seen them before so it was unique looking.

Have fun, I'm sure your son will be most pleased to see black on the roof - it'll definitely set the car off.