Axle swap for a 1991 firebird.

Helping my son with his axle swap.
First of all, this bird is a 1991 firebird T-top with 5.0 TBI, auto, with rear brum brakes. The only up grade we did is add a 6 AL MSD ignition box with matching MSD coil. And now time to do the axle. The one in the car is making a whining noise.
Anyway, this replacement axle has disc brakes, not drum brakes. all the pices are their for a disc set up. Do we need to change the master cylinder and/or proportioning valve?:help: Or will it not matter?:thinkin: Will it just bolt in?:xfingers:

the praportioning valve is different call the nearest junk yard for swap info the only thing is u might have to put a manual praportioning valve on witch is a hole lot better anyways .

proportioning valve is different i believe, master cyclinder shouldnt matter.

runs searches on www.thirdgen.org

Thanks for the input.:) Well just found out axle is not posi. Oh well up grade later.
Any GM part #'s for the valve? A manual valve? Is this available from bear brakes?
Just want to make sure this bird will stop. My son has a lead foot.:drivin:

just get used parts, hawksthirdgen certainly has some, maybe try www.thirdgen.org