I found a nice site about the F (and F2) meters and finders:

I now have a waist level finder like this one:

I think I'll try to find a chrome prism finder for my camera:

I might even try my F2 Fhotomic S metered finder sometimes, but then: that wouldn't be an original set from 1967, would it?

So, anyone has a F Eye-level Finder lying around he wants to "donate" to my small project? I'm open for suggestions ;-)
Or a broken Nikon F with a serial number from February 1967?