Pure Magnum swap

Good luck with it. I'm still working on mine. Dropping it in is a relatively simple process. Grind a notch in the trans. bellhousing, elongate a flexplate bolt hole, then attach engine to chain hoist!
Currently, I'm working on the fuel and exhaust systems. I used the original ECM, PDC and wiring harness. I would recommend using the PDC just to simplify the wiring and also to rewire headlights, fuel pump, etc. I took the opportunity to rewire my ign. switch and remove the ammeter from the original wiring. That way you can use the alternator wiring already in the new harness.
My engine came from a 2001 Ram and had the big airbox on top of the throttle body. I used the Durango throttle body air hood and attached a cone-style K&N filter. You shouldn't have that problem, but it's difficult to find a good place for the stock air box in the engine compartment.
Don't know about your existing radiator, but on mine the original waterpump lower connection was on the driver side. I had to find a different radiator. I'm also looking at going with an electric fan setup.
I haven't gotten to the serpentine belt yet. Mine doesn't have power steering or air.