I got one of those and a radio support bracket to clean up also. Buddy has some wheel bright, an acid you spray on and sit for a couple minutes then wash off. Said it worked great on aluminum wheels. Might try it.
Zinc wont stick to brass or aluminum or pot metal. Great for vac advances I did a prestolight housing for a guy came out really nice and it does not flake off like chrome does. Just have to buff it out after plating it.