Generally speaking, the best spray paint for metal is hard-wearing enamel. Its oil base makes it somewhat slow to dry, but it ...
While you're at it, sand all the other areas you treated for rust to smooth them out and prepare them for painting. Any spots you've sanded down to the bare metal must be primed before you paint ...
The only problem that we come in contact with is our alkaline paint stripper actually eats soft metals. So if there's aluminum, magnesium, or a pot metal on the car, it'll react and it'll dissolve it.