Hi NPSDF05,
They are actually available through any of the typical Mustang stores and speed shops. I buy most of my stuff at Mustangs Unlimited, Atlanta. Service is very good, people are knowledgeable, and delivery is very quick. Even large orders often go out same day. PI2 is $80. FT2 is $37. Pertronix part # 91261 for the "C" type rotor drive (dual advance) and #91266 for the "D" drive (Load-O-Matic).
Don't forget that you need 12 volts to the Ignitor for these to operate correctly. With the FT2 coil (12 volt) the best / easiest way to do this is to simply remove the ballast resistor (under the dash in the red line bewteen the ignition switch and the coil). Before you go looking for it, have the voltage at the coil checked first. Many of these cars seen to have lost their ballast resistors over the years. No need to look for something that isn't there.
Steve