Buckeye, I have done the same thing you are doing now. You can use your original pedal bracket and fab a new bracket for your dual master cylinder.
I used a dual master for a 69 mustang (drums front & rear) it works very well. I'll email you some pictures of my bracket that I fabed. (Sorry I can't post them here, long story)
Be sure and check out the links there is some great information there.
George
