Personally I would just wet sand it with 320 grit wet sand paper in the direction you want the brush finish to be in . The aluminum I have glass bead blasted in the past seems to get stained easily and the only way to clean it is to bead blast it . The best finish would be to anodize it after you bead blast it . here is a link to a home anodizing kit and tips .
http://www.focuser.com/atm/anodize/anodize.html