Wiring started changing heavily in 2004, as well did other things. I want to say the smart junction box came out around this time, which I believe is the GEM's replacement.
If this is the case, this massively over-complicates things and makes the job harder. In all honesty, I would just use the original harness from the original vehicle if only to make life easier.
Bottom line: Possible? Yes. Any benifit? Absolutely not.
Though, do keep the old harness around. There's plenty of wire in that harness that can be reused.