Help with Rallye harness replacing standard harness 70 dart

You are trying to use a 74 harness in a 70? WAY different. And 74 had the much hated seat belt interlock

Regardless of year/ options, you simply are going to have to sit down and do a 'wire by wire.' Also realize that from ?? 68ish to 70 whatish ?? service manuals there was a mistake regarding the yellow start wire and the horn wire where they go through the bulkhead. This is easily resolved.

So far as ralleye, if you can post a good shot--or maybe two shots, of left and right of the cluster, the functions are easy to figure just by looking at them. Then go to the harness and figure the purpose of the wires, AKA what is power, what is oil sender, etc etc