I believe they will. Logikfive had a set of 15x8 on his 78. I think he still has them on there.
As for paint, I'd just use a quality black gloss paint and call it a day. I'd prep the rims by scuffing them with a green scotchbrite and then go over them with a good wax/grease remover as there's no telling what's on those rims you're getting.