I have had at least one Pertronix system installed for more than 10 years.
I had minor problems with 6v & 12v Pertronix systems on 235s/261s until I took two "precautions":
6v & 12v system: run a ground wire from a distributor-cap-clip-screw to the coil-to-head-clamp screw/bolt.
The distributor ground might be poor/unreliable - that ground is critical.
Also, if you have a 12v system and a 12v distributor that needs a ballast resistor, follow carefully the Pertronix wiring instructions (found in Tech Tips on their website).
Nonetheless, I see no performance advantage to a Pertronix or a HEI ignition installed on a standard/normal-use Advance-Design & New Design GM engines.
And, no matter what the ignition system is, I now carry a tested/tuned spare distributor as insurance (many years ago, I experienced failed condensers and points).
