The conversion is pretty simple, remove the wiring harness of the system, you can leave the sensors in the intake, they aren't doing any harm once disconnected. Distributor has to be changed, one with a vacuum advance is best, and sorry, the carburetor has to come off, it has some inputs to it from the lean burn and there is no ported vacuum port. A matching 400 cubic inch stock carburetor will work just fine if it is not a lean burn setup, otherwise an Edelbrock or Holley will work just fine, both are pretty easy to tune. Several routes to take with the distributor, aftermarket or stock electronic ignition is available, or a stock distributor (non lean burn) will work, several aftermarket conversions for stock distributors out there, or Accel, Mallory, Mopar Performance to choose from. Given you aren't hopping the engine up and it is a low compression engine to start with, least expensive that fits the application and you are fine, a distributor from a 383 is the same for the 400. As far as wiring goes, get a wiring diagram for a 72 Dodge of your choice, follow the wiring for the electronic ignition, box, ballast resistor, etc., you will notice the simplicity compared to the monster in there now.