Will a 2009 3.5 replace my 2007 2.7?
 

My son blew the 2.7 in his 2007 Charger SE, and I bought a badly wrecked but running 2009 Charger SXT with a 3.5 for a donor car to get the whole drivetrain to the rear end and computer/harness. When I ask questions locally, the dealership mechanics say the sawp won't work because the 09 has integrated electronics, and to put in another 2.7 (not happening!) Different gear heads tell me different things about how easy-to-complicated it is to make this particular pairing work. What all has to happen beyond swapping drivetrain and computer/harness to make this work, in detail if you know please? How much of the electronics do we have to change to use the 09 integrated computer on the 07 body (which/all harnesses?, fuse and relay centers?, abs, dash cluster, ac controls, radio, window and mirror controls, seat controlls, any wiring under the carpet, etc)? Do we need to move any mounts, bend ac lines, change power steering reserviors, splice or lengthen any part of the wiring harness, or anything else? I am mechanically inclined, but this just ain't like the old days when I could put a smallblock v8 in just about anything and have it running in an afternoon!