Mancini Disc Brakes

I assume you mean the MBM kit? If so, I have a buddy that put the big bolt pattern kit on his '72 Scamp. He is completely satisfied with them.

15 years ago I installed the SSBC front disc brake kit on my '71 Dart GT. It was a very complete kit, albeit expensive ($820 if I remember correctly), that was a breeze to install.
FYI, I have factory 14" X 5 1/2" Rallye wheels up front which clear/fit perfectly. The factory 14" X 5 1/2" STEEL wheels do not fit the SSBC front disc brake kit on my car (caliper interference).