Going back to Chrysler ignition

My first test would be the pertronix if voltage is indeed your problem, plus it's a good back up from what I have seen and experienced. Last time I hooked one up it sure woke up my older brothers 67 Mercury Calenta. 289, looking a hole lot like the 67 Fairlane ( RIP brother Ken)
The Pertronix is so simple. Basically a magnetic switch. Just a pulse to trigger the coil. It's an electronic replacement for the points. That's it. No amplifier, no multi-spark. Nothing extra that you don't need. And now days with the poor quality parts, the points aren't the issue. It's the condensers that are junk.