Do NOT bead blast!. You will never be able to polish them. The polishing process is simply replacing big marks/scratches with successively finer scratches until you can't see them anymore. Bead blasting will put relatively large dents in the metal. No amount of polishing will hide the stippling effect.
Unlike Japanese bikes, the aluminum is not coated, so you get directly to the polishing. On a coated piece you would have to mechanically or chemically remove the coating. I use Jasco paint remover. Depending on how bad it is you can start with an appropriate grit of emery paper. I usually start with 400 or 600 grit and work my way to 2000 grit, but if it's not too bad I may start with 1200/1500/2000. Then any metal polish and a buffing wheel on a drill motor/drill press/bench grinder will do the job. You'll be able to find various grits in polish. Start with coarse and finish with jeweler's rouge. the process is tedious and messy, but curiously relaxing. Beer helps.