A standard blasting cabinet is not suitable for vapor blasting. Aside from using pressurized water, it uses a variety of media. And not all services offering vapor blasting are the same and their results vary widely. Properly done, it leaves a peened finish on cast aluminum, but that will not withstand time without regular maintenance.
In your cabinet, glass bead for stripping and prepping the pieces for paint is likely best. It will strip paint and oxidation but not tear up the base material especially if you maintain an acute angle with the gun to the work piece.