If your existing switch is still functioning properly (they do get old unfortunately) then the most obvious under-hood wires will be the Green w/red stripe (voltage regulator) and Red w/green stripe (ignition coil positive) for power in RUN and START.
However, the ignition coil wire is the end of a resistor wire, so will gradually keep heating up until the resistance lowers the working voltage to about 8-9 volts. If the FiTech can work with this, then you're good.
Personally though, I don't like using the ignition circuit just in case your equipment might take away some available current and lower the performance of the ignition system.
So my typical go-to is the Green w/red of the voltage regulator.
I don't think they had them in '69, but some years had a carb-mounted anti-dieseling solenoid that had power with the key in RUN. Pretty sure it was not powered during START, but not 100% sure about that.
In a pinch, you can also take power in START from the small terminal on the right hand side of the fender mounted starter relay/solenoid where the small Brown wire connects. It's powered by the battery just during START so can act as a backup in case either your ignition switch is failing, or you can't find a really good source for your White FiTech wire.
Not sure where members here are actually connecting theirs to. I don't run one, but those are the typically available circuits under the hood.
You could always create your own too, by splicing into that connector or wire at the back of the switch itself. It's the one with the two Green wires on a common connector.
Good luck.
Paul
