I don't imagine it's very hard. You'll probably have to find out as you go. I am also adapting 4WD to my truck, but I'm using a '68 GMC as a donor. Surprisingly, except for slightly different spring locations (1 inch different) and different shock perches, there isn't much difference at all. Everything on the rear axle still attaches to the spring. Technology just hadn't changed much in 16 years in my case.
The front axle is nearly as simple. It too simply attaches to the leaf springs with the U-bolts. Make provisions for the different shocks and you're almost in business. In my case, the steering box actually resides in the front left wheel well rather than inside the engine bay.
There's a little bit of welding, but nothing a 220 volt mig welder or arc welder can't accomplish. Maybe a 110 volt mig would work, turned up all the way and with patience. I think that can go up to about a quarter inch in steel thickness.
