Heres a tech tip on the harness, as i installed 2 of the painless harnesses before. One in a 60 el camino, and one in a 63 dodge town panel. Get a bunch of wire bread ties to hold the wiring together as you group and route it. Makes things easier. When satisfied with its routing remove the ties one at a time as you wrap the harness. Also wire up one circuit at a time, then only connect power to test that circuit. One circuit at a time. Make sure all of it works prior to wrapping the harness and terminating the ends. Leave a service loop before terminating the wire ends this way if you have to repair a connector later you have some extra wire to do that.
On the magnum heads i would get visegrip plyers and jerk those sparkplug tubes out of there. They can become a real pain in the *** with stuck spark plugs on a magnum. Ask me how i know.
PM me if you want a bunch of new bread twist ties , and i will send em to you.
