72 duster firewall wiring questions ???

To add that relay could I just cut the brown wire back I plan to use for the distributor and run it to the relay as the trigger and power the distributor off the relay which would be fed 12 volts from a wire off the starter relay + battery terminal...? That would be pretty simple, but would it fix the voltage drop if there turns out to be one? Sorry if it seems like I am kind of thinking out loud here...#-o