I don't believe that De Rosa dates to 73'...it looks mid-80s to me. Interesting, few De Rosas of that period had chrome fork crowns.

if you want a beautiful bike, paint it. Otherwise, I wouldn't. It's not a rare enough De Rosa to really be a show piece, you won't get your money out of it and it looks good as is. I'd ride it and enjoy it for the fine Italian you have.

Edit - decal is SLX - so it's 84' or later. Decal looks original and consistent with ic lugs and double bottle braze ons.