I have heard that the factory original paint can work well as a primer. I just recently painted my HAF 912 inside, but I did the sanding/self-etching primer/painting and it looks pretty good. Only problem is I did not take it apart so it does not look as good as it would have if I de-riveted it and then did it.
I think it would turn out okay if you just put a few layers and then maybe a few clear-coats over that and let it cure for like a week or two. You will have some issues sliding some of the removable parts in and out though.