You won't be able to mix and match the drivetrain components... THe engine, trans, and transfer case do not swap between the units, not to mention the wiring, ECU, GEM, et. al.
If you want to convert yours to 2wd, the donor vehicle will be a perfect source for the front end components you will need. However, it will not be a good convert for a V-8 4x4, unless you're looking to essentially swap the whole drivetrain (the motor's blown, and you need a 4x4 front end, manual t-case from an F-150, and trans tail from a 4x4)... Not worth it IMHO.
or 350, you can swap your parts, then have the same junkyard haul it off for $350, making your net cost zero.

Now, keep in mind you will have quite a few issues with the electronics too... a dealership *may* be able to modify the GEM and ECU parameters to make the system think it's a 2wd, not a 4x4, otherwise there will be some other electrical gremlins to find.
In all, it's easier said than done. IMHO, you're still better off selling them both and buying a 2wd if that's what you want. Converting them is more trouble than it's worth!
-Joe