Brake Booster?

I have a 72 Dart with a 440, fenderwell headers and 509 cam and I have disk brakes front and rear,front is from a 75 Valiant K frame and all, and the rearend has Willwood disc on the narrow 8 3/4. my eqestion is do I have have to run a brake booster with it, the 8 in fits but it is right against the headers, maybe a 7 in will work, or can I just run the master cyclinder with a shield under it, I was thinking of that redbore master cyclinder, but that thing is not cheap, and I have heard bad things about it, please let me know.