Electronic ignition was a $25 option on Mopar V-8's starting in 1972. It became standard equipment on all Mopar 8 cylinder cars in mid-1972. Starting with the 1973 models, it was added as standard equipment to the 6 cylinder engines, as well.
The reluctor replaces the cam lobes of the traditional distributor. Instead of having the cam lobes opening and closing points to excite the ignition coil, the reluctor breaks the magnetic field between the pole piece (magnet) and the pickup coil, to trigger the control box that excites the ignition coil. The ignition coil output is then directed to the proper cylinder via the traditional rotor and the distributor cap.
1972 models had a separate wiring harness to support the electronic ignition. By 1973, that harness was integrated into the car's main harness. If one can find a 1972 donor car, moving the electronic ignition onto an earlier car is duck soup. It is pretty much a plug and play operation with that separate wiring harness. The point plate of the earlier distributor, and the newer plate that holds the pick-up and pole piece, are drop-in replacements for one another. If you decide to use the old distributor, you swap the point plate for the pick-up plate, and the distributor camshaft (moving the reluctor at that time), or else you need to move the old timing weights and springs into the new distributor to preserve the older engine's spark curve.
The Lean Burn system is often maligned, but when it worked, it worked well. By today's standards, it is crude. It is an analog computer system, which is temperamental in laboratory circumstances, when you subject it to the day in, day out, 100 degree + temperature swings found under the hood, all bets are off. But when it worked, it delivered excellent fuel mileage and performance, while meeting clean air standards and delaying the use of catalytic converters by a couple of years.