Aloha Fred,
I've used an aluminun hi-temp paint, it looks very silver, shiny when applied, but cures to a dull aluminum appearing finish after it is heated a few time. I've found it at hardware stores in small half pint cans. Wire brush and remove as much corrosion as possible. I use Ospho to pickle the surface before painting. My experience however is that painting only last a few years before it starts show rust. I'm sure there are other more long lasting finishes available.
I've recently been using stove blacking on brake drums and exhaust manifolds. It seems to last much longer than hi-temp paint. I cures to a matte finish, black to dark gray in color.
Safety Fast,
Dave