For retro saddles I like Flites, my Brooks Pro, and the Regal, but not Turbos. The Rolls is a similar shape to the Turbo, but my 'taint prefers its ample padding. Just can't handle the Turbo. I have no experience with the Brooks Colt and think they look goofy.
Just going on looks, I'd put a Regal, Rolls or Flite on that bike. In some kind of brown.