Re: motor swap?
If I remember correctly, the intake off one of those is desirable over regular truck's. You will have to procure different motor mounts, transmission-to-transfer case adapter, 're-route transmission cooler lines, New wiring harness(if you want stock gauges to work) , New exhaust pipes, I believe ,if you build a stout 4.3/5.7, 4L60/th400 and upgrade turbo and ECM, you come out ahead in the $$$$ department. LS is aight but need deeper pockets to swap one in than to rebuild even the 350 engine. They make those 4.3 blocks like the " M" sbc stuff too , you know. Forget what they call 'em. Look at "parts for sale". Not to discourage you... just info.
You might also consider the Chevy Colorado with 5.3 and gets as many parts from donor vehicle as possible. Radiator, shroud etc.