Body swap or drivetrain swap?

[Nova70]

I got ahold of an '03 duramax at auction. The body is trashed but frame and all drivetrain is still good with 90k. I took it to a shop to check if the frame was bent and they said it's still straight. I don't know if I want to put the Allison and the Dmax in my truck and upgrade my axles, or if I want to put my truck on the newer chassis all together. It was a crewcab longbed truck and Im looking for a Burban body to chop for my crewcab.

What would you do?