Hi there Richard,
I would say that if you cleaned that up and installed it, you'd be darn near Concours correct. The only kicker I see in the way of this would be that I also would expect to see a Engineering Part number stamped into the side of the flange. All the factory ones I've seen over the years had this in them (faint in a couple of instances), whether it was a Mustang, T-Bird, etc. I am not "certain" of this however. It took me several years of searching and research to finally find both the correct blade and fan clutch setup, as they were both missing when I bought our car. The MustangTek site was a VERY GOOD resource in this effort. The blade number is spot on, as is that style of clutch it looks like from that site. Deciphering the code on the face of the clutch, I'd need some help with. Might want to also double check the length of that clutch stem too. Knowing how thorough you are, most likely you've already done this...! The finish is fine on the clutch stem too (natural). Nothing that a little Boeshield won't help to maintain.
Take care!