3.0L to 3.5L 24v SOHC Engine Conversion ...
With the new 3.5L installed in the engine bay and bolted back up to the transmission there are only a few things left to do.
The power steering pump, alternator and air conditioning compressor need to be reinstalled. Doing this before reinstalling the radiator gives plenty of room to work and assures that you won't accidently drop the compressor up against the radiator core bashing the fins or maybe damaging a core tube.
After all the machanical parts are reinstalled it's time for the wiring. Since the 3.5L uses the same sensors as the 3.0L (except for the IAC, TPS and cruise control stuff we've already taken care of by swaping complete throttle body assemblies), reinstalling the wiring is just a matter of reversing the removal process. Be careful not to loose the rubber seals inside the plugs!
A few years ago the factory clutch fan assembly on my 1997 Montero Sport was removed and replaced with electric fans and a SPAL controller so the only thing to reinstall in the front is the radiator and radiator hoses.
The last two things are to fill the engine with oil and coolant. At this point it's time to double check everything and make sure nothing was forgotten and everything is tight. After that it's time to start it up and take it for a spin. The engine we used was used and had 50,000 miles on it so there isn't much concern with breaking in the engine in the conventional sense, but it's still a good idea to run it for a few hundred miles and then drain the oil, replace the filter and refill it with fresh oil. In this case we had the valve covers and oil pan off so there was no question of whether there was condensation or other crud inside. It's not a wise choice to trust that the salvage yard didn't accidently get something inside while pulling the engine or after sitting in storage in an unknown environment.