SSDVC, Black beauty and Black Diamond are both coal slag products, great for blasting steel, but I'd say way too aggressive for aluminum. Also, be careful with both of them, they tend to have short "string like" pieces mixed in that easily clog your nozzle. Always sift it first. I would only use the fine size, not medium unless you have a big sandblaster with 1/4" or larger nozzle. For doing aluminum I'd say wallnut, glass bead, plastic bead or soda blast. Also remember to clean thuroughly if soda blasting, it leaves a residue that must be removed before priming. Then use a 2K epoxy primer or seft etching primer for best adhesion to the aluminum.
Blasting will work much better than chemical strippers. If you blast the areas you want to polish, sand it afterwards and get progressively finer until at 600 grit, then begin polishing after that.