4x4 and possibly 5.9 cummins swap build

[Rednwhitec20]

Hello, I plan on selling my current truck to my step dad and buying a k20 that needs restored. I am wanting to put a 94-98 5.9 cummins in it with an nv4500. I'm not sure if I can afford to do a cummins swap. I know I will have to atleast put a new front axle to support the weight. I will also box the entire frame while it's apart. I plan on atleast a 4" lift so my pan will clear. Now, will I also have to swap out the rear end or will it be strong enough? What else will i need to modify? I plan on using it as a DD but it will also work when needed