Electronic ignition conversion need help!

First, you haven't searched because there are a gazillion posts answering your exact question. I find searching from google best.

The $45 HEI distributor is your easiest & cheapest option (ebay, Steve White Perf & others).

Forget the 70's Mopar ECU. The GM 8-pin HEI (85-95 V-8 trucks, -93 cars) is much better and simpler to wire. I grabbed parts at the junkyard years ago and posted, then TrailBeast starting kitting as new parts. Not my idea, read up on Megasquirt site, as I did. But you will need a 70's Mopar distributor. The GM 8-pin has the big advantage that some engine controllers can command it for spark timing, ex. Holley Commander 950.

If determined to use your 1965 distributor, you can stick a Pertronix ECU module inside it. Use the better Ignitor II or III. That will cost more.