I did my wheels and bits of frame 4 years ago with smoothrite gloss black rattle cans. I cleaned with mucoff then set about offending areas with paraffin and a tooth brush then attacked with a small wire brush then smoothed with 250 grit wet n dry, another wipe over with panel degreaser to make sure no oily finger prints left on surface then sprayed, no need for primer with this paint. Still looks good and shiny. Don't put much on each coat as it will run, build up in thin coats.
Hope this helps, worked for me.