You need to find a gentle l method of cleaning the case once it disassembled. Wire wheel will not restore the finish nor will most of the blasting options. Walnut hulls at low pressure would likely be best. Rattle can paint will look OK short term but will discolor and possible crack and peel at some point.
Consider some of the methods suggested for aluminum intake restoration here on this site for more ideas, like deep cleaning and brushing with a nylon brush. As often happens there is no easy button or short quick path to doing a good restoration