I would also look into the smog legality of this swap in your area. I would highly suggest keeping any factory emissions controls from the newer donor as well as making sure that the donor engine setup is from the same series. Places like California for example will not allow a truck engine into a car for example. Even if that 6.0L was replacing a gas guzzling smog era 454, it is still illegal as much as that makes sense. In California that 6.0L would have to be out of a Vette, Caprice cop car, SS, G8 or GTO in order to go into a car. It would also have to have all emissions items transplanted such as evap, cats in factory positions and all 02 sensors. Then that 6.0L would be smog tested as the donor vehicle once the smog referee gave it his signature of approval. Just something to be aware of.
Even though I am in Texas, my 97 with the 383 has all the factory smog stuff in place as well as CARB EO equipped headers. When I added the newer PCM, I also added a fuel tank pressure sensor and canister vent solenoid and hooked the fuel level sensor up to the 0411 so that all the emissions monitors would become READY.
The 87 G20 6.0L swap is also setup the same exact way. I picked a 2006 6.0L that came from the facyory without EGR to simplify the smog.The cats on it are on the driverside but they are exactly the same length away from the face of the headers as they are on the stock 6.0L 2500. The 87 has a newer charcoal canister on it with the correct vent and purge solenoids and evap pressure sensor. In theory someone could buy it, take it to the smog referee and smog and register it in california.
I saw the light in the tunnel on the coming smog situation before either of those swaps.
