The C4 M/C is designed to work with rear disc brakes anyway,it doesn't care what make the brake calipers are.
Even if they are F*rd ones!
It should provide enough pressure and volume for your conversion.
I don't see a problem so long as you use the correct proportioning valve for that M/C, alternatively you could install an adjustable one.
It's the fronts that do the real hard work.
Approx. 80% of braking is provided by the front(usually)
