As mentioned by others, the clear will not adhere perfectly and you will be chasing rust. Save yourself the ass pain and paint it.
Hahahaha I hope you never get your keyboard fixed, Ian. It's too funny reading your posts lately! As for the car...You have one of the nicest examples of those Chevy coupes on the H.A.M.B (in my eyes at least) One of my favorite things about it is the color it's wearing. De-chrome it, shave it, nose and deck it...but for the love of old Chevrolets and my personal sanity, please paint it...
shoot it in a deep custom pearl, or step up to mirra chrome or wahtever its called. thats a nice car, give it beautiful paint if youre changing it.