ED9man

So I am hoping to do my rear disc swap soon. I am probably going to try and find rear disc brakes of a 90 or 91 CRX. Are they the same as the rear discs (if they have them) off a same generation Civic EX? Because I am thinking about saving a little more and putting the bigger front brakes off of a Civic EX on my car. I am just wondering because if I did it this way I would probably want to use the Civic EX proportioning valve.