Wow, love the wire nuts
The HEI drops right in, it's self contained. You need to swap your current dizz gear over to your new HEI to prevent dizzy gear wear issues.
The HEI only requires a switched power wire. I would run a wire from the ignition switch and wire in a relay and get power right from the battery....the HEI can draw a lot of current. (not using wire nuts of course
edit: forgot to add you will need the correct spark plug wires to fit the HEI.