Ok I am finishing up the wiring on a hemi swap that somebody else started 3 years ago. In the instructions the supplier of the harness says that old style mopar ignition switches will not work, because of the drop in voltage as you turn the key, they recommend using a push button switch for the starter and not use the stock switch too activate the starter. You guys that have done the swap, what did you use? Stock ignition switch or something else?

Stock switch, no issues, but I’m using the MP wiring harness
There's no voltage drop from the ignition switch between ACC, Start, or Run, that only happens at the ballast resistor.

Have installed a hellcrate combo along with the stand alone ecu / wiring kit and with the stock switch my Challenger works flawless.

I have the gen 3 swap and run my original ignition switch from 1974. never any issues.