[FWB]

the original ford alt. was externally regulated, it shouldn't matter 55 or 100 amp but it must be the old style 3 wire. i have a diagram in my photos from a ford manual. the size of the original type alternator may also cause mounting issues(clearance) not to mention ease of getting a new alt if yours craps out. i went with the smaller size one wire to keep the wiring simple and to be able to get a replacement alternator at many different places.

good luck