not a pro - just anecdotal info on a couple of times that it didn't work out,
Clear is not the problem - magnesium is.
example one - TJ had a set of large and larger magnesium Halibrands for his Corvette - sandblasted the wheels to take them to the powder coaters for clear coat. The wheels started to grow hair before he could get them to the powder coaters the next day - ended up going with gray.
example two - talked to my friend Roger at a local swap meet - he had a beautiful set of clear coated polished vintage Halibrands in his booth - The wheels had some time on them after they were powder coated - they were turning black under the clear.
Not sure how it's done on restorations...