Unfortunately, the "maintenance polishing by hand" methods I've seen don't do a bit of good on oxidized surfaces. You really need power tools to cut through & remove the oxidation accumulated over 35+ years. The results are very splotchy not worth the effort - especially if you have evidence of failing clearcoat. The areas of aluminum that have been exposed to the elements the longest are the most oxidized with areas recently exposed have little to no oxidation which gives the aluminum a "peeling sunburn" look.
There are only a few ways to get everything "even looking"...
- strip all the remaining clearcoat off & as you call it "deep polish it" - then either:
- re-clearcoat it to get another 10+/- years out of it before you (or the next owner) has to do it again,
- don't re-clearcoat it and maintain the polish as needed to keep the shine glowing
- don't re-clearcoat it & let it oxidize - at least it will be more even that the "sunburned look" and will look good for 10-15+ years depending on your environment & it it's stored indoors or outside
- strip all the remaining clearcoat off & have it walnut or baking powder blasted
- this will give you a more muted, not-so-bright finish, but it will still oxidize & get dull over time
- it's also slightly "textured" from the blasting - looks sort of like annodizing
- strip all the remaining clearcoat off & have it acid washed
- this will give you a more muted, not-so-bright finish, but it will still oxidize & get dull over time - but the surface is smooth
- the acid wash - if not done & neutralized properly can cause leaks & seam sealing failures
- strip all the remaining clearcoat & paint it silver
- this will give you an even finish that will not oxidize like the raw aluminum, but will need to be waxed like a car.
Of course, just regular washing & waxing (with something like Nu-Finish) will keep the oxidation from progressing further and be the least cost & effort.
Good luck in whatever you decide to do!