The trick with the five liter swap is that you will need to run a carb(doubtful if the gas mileage will even compare)and who wants the hassle of a carb in cold weather?And if you want fuel injection shell out another $1100 for a Holley TB system or hack your electronics apart to splice in the brain for whatever Fi 302 you chose.
I like the idea of rodding the 2.9 because the truck doesnt get left with half a wiring system or the electronics from the lobotomy you performed on your donor Thunderbird wrapped up somewhere.But to each his own.
Up here where I live,the pain of a carb in winter when it's -35 for a month outweighs the power of a 302(which you can get out of the2.9 anyhow,with work.)Make up for the lack of torque with some lower gears.And you end up with a good drivable truck.

 

There is one thing that no one has said,4.0L..Find a good 4.0 do some head an intake work on it.A new cam get one for what you went to do with the truck{high HP or low end grunt }Replace the timeing chain{a know problem}.Then you dont have to do alot of wire swaping {yes you do have to do some}.get a good chip or a reprogram on the computer{the one from the donor truck}With this swap you dont have to do the drive train swap.The 4.0 will bolt right to the tranny.

 

Would the computer nervous system from a 4.0 ranger swap into a B2 and hook up to everything else in place of the 2.9 Brain?or is the 89 up dash and gauges needed for a direct swap over?

 

Im not sure which wires need to be changed except for the MAF and crank triger,and coil pack.Also the computer..I think the guages on the Gen 2 BII are the same as the Gen 1 Explorer.

 

The Dash is the same but I have the old style dash,So would I need to swap it out?Or are the wires plicable .I do like the 88 and older Gauges..
And with the computer..Do you just power it from the battery and hook all neccesary Explorer parts to it and leave the B2 computer in the truck to deal with everything but the engine?