Actually, thinking about it more, I would guess the black was sprayed on to cover up some damaged paint (probably from heating the tubes to remove a stuck seat post), so the original paint will be gone anyway, unfortunately.
I think you've got a mix of 1050 and 1051 parts. I would think the Exage levers are also original as they are the same age, just cheaper than the 105 levers.
Lots of people have sets of wheels around, so it might not actually be that hard to find a replacement rear to match the front - depending on what rim the front one has on it, I suppose.