Definitely not the easiest thing in the world to do with the engine in...............
__________________
“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
I know, but was trying to be lazy about it. Might have the shop just do it when they do a couple other things on it.
If you are paying a shop to do it, and they don't drop the engine, the cost just in labor time is going to skyrocket................
__________________
“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
In my experience it comes down to just that....experience. If you have removed a harness from an engine that was out of the car, then you know how it was run and where the "hidden" connectors are and with that knowledge you can work around in the engine bay - assuming access above, below and through firewall - to change out the harness with the motor in the car.
Are you working with a 2.7 out of a 2000? I ask because I once took a 2.7 out of a 2000 and tried to drop in a 2001 2.7 into that 2000. The wiring harness from the 2001 would not work seamlessly with the 2000 computers. One problem was the temperature sensor in the 2000 had four prongs, whereas the 01 had a two prong connector. A second problem was with the tiptronic thumb shifter not working. Once I took the harness off the 2000 2.7 and put it on the 01 2.7 everything worked fine again in the 2000.