Willem, I just researched vintage Mustangs, bought a 1965 and have done some work on it.
Many here were helpful to me along the way. So if we can help you make an informed decision, just let us know. I know I'd like to give back to people like you some of the good stuff I got here.
One thing you may want to consider as you buy is that the original pickups are very good for most playing purposes, and the in-phase-out-phase switch lets you get some very cool tones...like Tele spank, but if you want to do screaming leads or shred, these pickups are a bit limited along those lines.
Best with your quest!