The ignition module is the key part of this upgrade. My first choice would be to visit your local wrecking yard and look for a 1974 to 1990 GM vehicle with a 4-pin ignition module (AC Delco D1906 or equivalent). I would grab the wiring harness and connectors from the distributor to avoid having to use spade terminals.
HEI Heat Sink
The HEI module generates a lot of heat that must be dissipated in order for the module to have long life. The PN 10474610 heat sink was used on later computer-controlled ignition systems but will work with the 4-pin module when modified with some new holes. You need to put a heat sink thermal compound between the HEI module and its heat sink to ensure that the heat transfers into the heat sink.
|ACDelco 10474610 GM OEM Ignition Heat Sink||Heat Sink Thermal Compound|