Since your car is a 72, I am going to guess it's a 2.0 or 1.6. The 2.0 can be made to make pretty good power (ask pintony) On the other hand, if it has the 1.6, good luck with the 100hp mark.
Your car came with the 6.75" rear. Limited slip diffs for those are about as rare as hen's teeth. If you are looking for better traction, you may have to go with an 8" out of a later model Pinto or a Mustang II.
FYI, the 71 2.0 was rated @ 100hp. That may have been due to the higher compression ratio of that motor. I think with basic hop-ups and a good rebuild/blueprinting with quality components, the 2.0 can make respectable power for a 4 cylinder motor pushing 35+ years old. There are quite a few speed items made for that motor as they are used throughout the Formula Ford racing series. Also, check out sources over in the UK and the rest of Europe. These 2000cc motors are very popular over there.
Good luck with your pretty little pony!
--Doug