The '74+ spindles, arms, spring cups, steering rack, etc. are all different than the '71-73 parts.
It would be less arduous IMO to work out some custom caliper brackets and keep the early front suspension, but also have a full machine shop at my disposal. There's a thread about that on here somewhere, I think relating to a Granada swap. It involved modifying a set of inexpensive GM caliper retrofit brackets to fit the early spindle.
AFAIK, the spindle nose has the same dimensions as early Mustangs, Granadas, Mavericks, etc so the rotors and bearings ought to fit on the early Pinto spindle.