Watch the floors, right between the frame section and the rocker panels is a great spot to see rot show up and people forget to look here. If you see rust on the floor, poke at it from the bottom to see how bad it is. If its soft or spongy, get ready to weld a new floor in... Get a 4.0 if you want a 6 cylinder. Save the time & effort of the engine swap... 4wd swap into a 2wd truck shouldn't be avoided, its actually pretty fun!
Yes, time and money are really the things that get in the way. That and an ever changing project direction. Its much harder to hit a moving target than a stationary one. Set a realistic end goal and build it with that in mind. Don't start with a daily driver goal and morph it into a trailer Queen rock crawler over time!!! Lots of time and money wasted in the process...