Re: 2007 column in a 1965 SS
You are embarking in a complex task if you have little automotive electrical experience....
You are correct on the basics.
The original vehicles have ignition switches that carried the full load of B+ power to various circuits. Depending on the position of the switch dictated what contact and ultimately what circuit received power when appropriate.
The modern switch only provides small currents to perform request functions to and from the car modules. The modern switch is NOT designed to work like the old switches and can't possibly carry anywhere near the current needed by the old car.
You will have to determine what is the "common" wire in the modern switch. This will have to connect to constant hot in the old car. A fuse in line would be preferable. Then determine what wire in the modern switch becomes "hot" with each corresponding position. I.E. when cranking, what wire gets connected to the common to output 12 volts.... This wire will then have to go to one side of a relay coil, and the common and N.O. contacts of that relay will then take the place of the original switch function wires. I.E. The relay #30 terminal will connect into the original large red wire that went into the factory switch. The #87 terminal of the same relay will then connect to the purple wire that originally went into the factory switch. This would carry out the "crank" function.
This arrangement will have to be repeated for each function that original switch provided, I.E. "on", "crank", "accessory" etc.
This will definitely take some time and planning on your part.
-If you don't stand for something, you'll fall for anything.