I have a 1958 featherweight chambered in 243 that came to me by way of my grandfather. Simply the fact that it was one of my grandfather's favorite rifles (and he was quite a gun crank) makes it special to me and one I will never sell. That said, I really do not understand the huge premium they bring. Quite frankly the sins of 1964 have been righted for over 20 years now with the classic model 70's, I am a major fan of my New Haven classic, and from what I have heard the FN produced rifles are some of the finest ever.
I would not trade a rifle that you know is a shooter to chase an unknown quantity in a vintage rifle if the object of the game is accuracy and reliability. If you want a pre-64, by all means save and buy one, but don't hawk the Kimber to make that happen.