No power while cranking

The sad part... owners have replaced ignition switches, ignition modules, and more, without first looking for voltage loss, what vein is bleeding. I'm guilty too. My current 67 model had a relay that uses only a signal from blue with white tracer coming from ignition switch to supply everything beyond it with full battery voltage. It takes a good bit of effort to wire one of these classics like new vehicles are wired. The 67 model didn't have that choke heater or anything else added to the contacts of its dash mounted ignition switch before I upgraded to electronic ignition, stereo and amplified subwoofer.
Because I had already seen the white harness connector from a better built column mounted ignition switch overheat and melt, I knew I had better take some load off of the 67 ignition switch I'm using.