That is one super nice Caddy. My dad owned a 58 Eldorado Brougham in white with a Stainless steel top. (this was before he married my mom). He said it was quite the divorcee magnet.
I have my doubts as well. The F&F version is quite chunky. That is not to say that you could not rework it and thin it down some. I would obviously need "rechromed" after such treatment.
I did one of these a long time ago. I made some changes you may wish to consider in your build.
I added a spare tire, made a strap/chain box and used textured paint for the deck.