Finding switched 12 volt source

I have to convert a 73 Duster from the OE ignition to an aftermarket box. Last one of these I did was 1999 or 2000. For the life of me I can’t figure out where I picked up the switched 12 volts to run the new ignition box.

I also can’t remember if I just taped off the original coil wires or what I did with them.

TIA
YR