Wiring Help 6.1 w/ factory harness

No this is done all the time, example hooking up MSD, HEI or other ignitions where you replace the ballast resistor. You hook the old IGN1 and IGN2 together

What you can NOT do is , example, putting a Mopar engine into another chassis which has no ignition bypass circuit in the switch, but does need one. A good example was my old Landcruiser, which used a Chevelle column, and 340 engine. I did use a diode in that old girl.

What you need to be careful of is "backfeeds," such as hooking together the ignition and the start line.