When I got my 70 Coronet I replaced the engine and forward light harnesses with the M and H from Year One. For the price it was not worth making something myself or bothering to repair the originals.
I did save the originals though. I seem to save everything. But looking at the condition of some of the wires I am glad I did the new install.
77 Macho Power Wagon LWB factory 440
70 Coronet 440 N code 3 speed