Need a little help!

I need to get a new master cylinder because I have done a front and rear disc brake conversion. I'm not an expert in master cylinders or boosters (and I understand you pretty much require a booster for disc brakes?)

My question is, will the following master cylinder/booster combo work in my '70 Dart? It mentions that the MC is for front disc brakes...but does that also mean it could be for rear discs as well? And I believe I need to go with the 7" booster otherwise I will hit the headers.

http://www.summitracing.com/parts/SSB-A28142/?image=large

Any help is appreciated, I've never done a disc conversion before so any insight is valuable to me!

Thanks,
Craig