In my case '88 Corvette discs are bigger diameter than my Mustang 2 fronts. The proportioning valve is not going to be the total answer.

I have been looking at 12" front rotor and calipers.


http://www.rjays.com/Brakes/MII-Brakes-01.htm


I am looking for smaller rear and larger front till the sizes look right.
Front rotors than can accept GM Chevy wheels is a plus also I guess.
I need the emergency brake mechanical too to pass inspection.