67 Dart, no lights
You say "aftermarket wiring" and then "follows original format." That doesn't mean much on this end. Is it a factory type fuse panel?
First thing is to find out what is working or not or bad fuses or not in the fuse panel, plain and simple. All that you mention "not working" should be powered at all times. That is important, as that eliminates anything which goes through the ignition switch.
If this uses older style fuses, be ware, as rusty, damaged fuse clips can lose contact with the fuse and cause a power stoppage. The same problems can cause heating, and blow a fuse because of it. Examine the fuse panel carefully. Probe for power.
In this case, using a test lamp might be better than a meter because you can wiggle and jiggle stuff and see an indication / change more easily.
Try to test "under a load" so your tests don't lead you down a false road. That is, a bad connection will often pass enough power to show "good" on a meter or light a test lamp. But if you turn on the switch to that circuit, often the load will cause the bad connection to stop carrying power, and you can then "see" it.
IF THIS IS INDEED a factory stock harness that has been modified for EFI, then go over to MyMopar if you have not, and download a factory service manual (free) as well as the aftermarket, 2 page diagrams availabe in the "wiring" section. These are not often as complete or detailed, but can be easier to follow.