Hey guys,
I've done a good amount of research on the 4.0 to 5.4 swap and I still have a couple questions I'm hoping to get some help with. I was contemplating building a 5.4 from an old navigator and piecing everything together, but then I found a few "complete take-out kits" from wrecked GT500's on ebay with pretty low mileage..

-Is there any reason I shouldn't go with one of these "kits?"
-Since I have an 06 Mustang, would I have to use an 07 GT500 pcm/drivetrain? I anticipate the wiring to be one of, if not the hardest parts of the swap.

Thanks in advance guys