Converting my front brakes to disc from drum on an a body using the scarbird conversion.I already have a disc bake master for a 1973 a body with discs. Now the prop valve i know i must change. Will this one from summit racing work?

http://www.summitracing.com/parts/CLP-PV-2/
and would i need a valve like this for the rear brakes with that prop valve?

http://www.summitracing.com/parts/WIL-260-3279/

First, you need a disc/drum master. The first link might work bu they do not give any specs so who knows. That second valve, NO, you do not need it.

Not too familiar with the scarebird setup, but on my A's I run 11.75" rotors and either 10" or 11" rear drums. For a prop valve I use one of two choices from the later M bodies, one is for a 10" drum rear the other for an 11" drum rear, to match my rear drum setup. Works very well.