Not so familiar with the '74, but i have to say BWM, HRM (xweb speak for Brown Wire Mod, and Headlight Relay Mod) Papa Tony and Bob Brown are the ninja masters at electrical, if you need in depth info. If your into the "stocker" all original thing, i'd look to Bob brown, for one of his "no-cut" relay kits. If you don't mind cutting up the wiring i'd check the xweb wiki for the brown wire mod and headlight relay mod. Since your local and i just did this to my car, I have all the tools and recent experience; I'd be willing to help with this, if you can drive down here.
Freaking sucks, The day i finished the BWM and HRM on my car i blew the head gasket. My wife still thinks if it ain't broke don't fix it, and thinks somehow the BWM/HRM blew the head gasket... Maybe on a karmactic metaphorical sense. So be careful once you start messing with it.
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