I am no expert on Pertronix, but typically when you install an electronic ignition, you must supply a full 12 volt source to run it rather than the 7-9 volts that comes from the oiginal resistance wire that supplies the existing coil.  That said, your old coil will burn out rapidly with the new 12 volt source.  So, rather than complicating the wiring by having a second source for the coil and ignition module, it is typical to install a 12 volt coil.  The larger the coil output, the better the car will run, so 40k volt output would be minimum.

When we changed theignition on the  200 in our 66 coupe we just got a new/rebuilt distributer and ignition box and modern 12v coil.  It only cost about $100.00 for everything and the parts can be bought/replaced from any parts house. I have used the pertronix units in old Jeeps and they work but if it fails than you have down time till you can get another. The electronic distributors bolt in like your points dizzy and the ignition module on the shock tower doesn't look bad.  You will need to hit the junkyard for some wiring though.