standard master with brake upgrade

Okay..... here are my questions. 1. Can i use a standard master when using a upc big brake kit on the front and r31 on the rear? Also i have put the booster on the firewall. Now the master sits differently. Will this matter??? I will put a pic of to show you

I was given to understand that 4 wheel discs required a larger bore master cylinder, I used a bigger one from a 626. I was also told later on by the certifying engineer that the proportioning valve should be taken out of the front distribution block so you have a 50/50 ratio. The original valve provides a 60/40 bias, the front discs need more pressure than the rear drums. My booster setup is standard so can't comment on how yours will go.
Cheers,
Len

Thanks everyone