Drop it in and provide it with a new copper wire from the the fuse box all the way to the HEI that is powered when the key is turned on (otherwise you couldn't turn the engine off). You can not use the factory ignition wire you are replacing because it is a resister wire that drops the voltage from twelve to eight volts (this is to lengthen the life of the points you no longer have). That is about it assuming you know how to set the timing.
It also has to be powered when the key hits "start". Ask me how I know.
You can back feed power off of the solenoid to the ignition to power it during the start segment. Points cars are already wired this way as the factory provided full battery voltage (which dropped under load) to fire the points when you cranked up the car.
Many people would come into my shop and complain of the car cranking up and dying the instant they let go of the starter switch because they were powered during start but had a broken ignition wire other wise.