I have no experience with a Mustang and a Pertronix unit.
I have been using 3 Pertronix units on 235/261 6v and 12v engines for as long as 16 years with no problems.
When I travel long distances, I carry new/spare points and condenser in trucks that have either a Pertronix unit or have points/condenser. Actually, I bought a $15 spare distributor that has adjusted/tested new points, condenser, rotor, and cap (and I carry a tested coil and ignition wires).
This "insurance" policy has not been necessary for my conventional or Pertronix engines (but, I like having insurance - I recommend this, no matter what ignition system you use).
