The 6.0 I got came out of a wrecked Denali, but the motor was still running and could be seen before it was pulled. I ended up paying less than $1K for it since the guy who did the work was buying 3 engines at the same time. Normally it would have been around $1200. The TH350 tranny also came out of a running truck, and cost $200. I wanted reverse manual shifting so had to buy a valve body from Summit whose price I forget. The output shaft on these is 23 spline, so your transfer case of choice needs 23 spline input shaft. The Novak adapter I had on the old 700R4 worked with the TH350, but wouldn't have if I'd gone with a TH400.
The engine doesn't come with all the accessories or exhaust, so count on sourcing those, along with a stripped ECM and tune.
Whether you need a new radiator depends on how the water inlets and outlets match up to the water pump. In my case I kept the radiator, but the hose routing meant I needed a new fan to fit. I also had to have the intake reversed on the block, meaning some minor rerouting of the fuel line. It's likely you may need a new fuel pump to have enough pressure. If you go with a fuel cell you'd do that anyway. The truck oil pan hangs down pretty far, so a Camaro pan was bought to replace it.
It's not a cheap process, so if the budget is tight it's not a good idea. There's always something new popping up to add to the cost.