My 69 bird have the original underdash wiring harness intact and uncut, and as far as I know, the resistance wire should be in this harness. Might be different with earlier years though. The wire from the coil to the starter is probably used to provide the coil with a full 12 volts when cranking the starter.

My problem is, when measuring using a voltage meter at the coil, it's still a full 12 volts (and even 14+ volts with engine running). Using an aftermarket 1.8 ohm ballast resistor just for security measures, but it shouldn't really be needed...