Using mustang rotors for 4.5" bc
I had the exact same idea to use the Ford rotors on my 69 GTS and just stumbled across this thread while searching to see if anyone has done it. Glad to know it works! One thing I have done to solve the seal issue was to make a steel sleeve to press on to the spindle/axle where the seal rides. I did this on my old 66 F250 truck when I converted to the later rear breaks and larger bearing hubs. There was no seal that would work so I just made a couple of steel sleeves on my lathe and hammered them onto the axle. Worked great.
My first thought to get the 4.5" BC was to redrill the 4" BC rotors but if you look at the hubs you will notice they are scalloped around the studs thus not leaving enough room to drill another pattern in between the 4" one. Filling the existing 4" BC holes with threaded plugs may work but can be problematic. The Mustang rotor is the way to go!!! Thanks for your efforts. Looks like I'm off to get some Ford rotors and get busy on the lathe.