Fiat 2800: for sure!
Viberti? My source says another coachbuilder, but I'm quite sure it's wrong. Looking at the logo, I can agree with you.
But are you able to prove it? The picture looks scanned from some book: is anybody able to find it and make a better scan or read the caption?
However, I think it's correct to assign the point to you, but I'd like also to keep the puzzle open still for a while, moving it to Pros.