HEI in a Mopar?

For all engines but the slant, you can buy a new distributor with integral HEI module for $45 to $120 (search ebay). Some have a coil in cap like old Chevy motors, which is the simplest wiring of all. You can pay more for parts from the same factory from tuner shops if you enjoy spending money. Use an e-core coil for best performance. For a slant, it is easy to roll-your-own (many posts, I did).

Any ignition system that uses a ballast resistor is old-fashioned and won't give as strong a spark. These include factory Mopar (~72-82), Pertronix Ignitor (I, not II or III), Holley XR700, ... For future upgrades, consider the 8-pin HEI module which will allow adding computer spark control later. TrailBeast's kit uses that.