About the best I've ever got with aluminum "black" is a kind of smokey blue-grey. Not a good match. Depending on the gloss and color, you might do as well or better with Rust-oleum oil based paint, or Brownell's bake-on gun finishes.
I've done a good job on small scratches, by filling the scratch with a small artist brush and the paint or Brownell's finish. Let dry or bake, and add more if necessay to fill the blemish up to the surface.