Gasoline Resistant Paint For Fuel Filler Neck

[cericd]

Seems the original in-cab gas tanks had a portion of the filler neck painted black (see pics below). I would like to replicate that look on my aftermarket tank. What paint would be the best and most durable for this application?

A pic of my original tank (one at top of pic). The paint seems to have been masked to stop before the ridge at the end where the cap goes.



A pic of another members tank where the paint extends past that ridge but not onto the area where the cap seats.