I sure hope that you have access to the whole donor car because there are computers and micro processors hidden in the wiring harness all over the car. The 4.6 engine and it’s transmission are a fantastic machine, but the electronics that go with it are a lot of what makes it work, and they can be a nightmare if they are failed or missing.
If this is sitting on a stand or something, be absolutely certain you know exactly what year it is, because the electronics were tweeked every now and then, so if you don’t get everything right, it will drive you blind.
I remember dealing with my 94 Crown Victoria, when it passed 250,000 miles, the electronics started to fail. WHAT A NIGHTMARE!!!!