Question about wiring ignition

[MrQuick]

The diagram shown is a general schematic for a starter bypass relay set up. The R terminal shown to feed the ignition is for the resister wire bypass, so the ignition system recieves a full 12v at crank the goes to resisted voltage(6-10v) after key goes into the run position.Voltage was resisted to reduce points burn up.
On your 69 Vette, there should be a yellow wire coming from your starter R terminal and runs to the coil B+. Now if you look at your coil B+ side there should be 3 wires, 1 white furry wire that goes to the bulk head, a yellow from the starter and a black wire that goes to a capaciter on the firewall.
If you need a full 12v, you can go into your bulk head connecter and remove the original B+ feed (furry white or grey wire) and replace it with a 14g wire.The circuit behind that is a full 12v feed(usually a 12g pink wire) from your ignition switch. You will have to rewire your ignition switch to get 12v while cranking, or run the bypass as laid out in the schematic you posted.