'73 cab/body on modern frame?

[slotard]

A friend of mine is probably selling his 2000 Chevy 2500 work truck before too long. It has a 6.0, auto tranny (I guess 4L80E?), 8 lug, has a few dents but everything works great.

He claims he gets close to 20mpg on the highway, while I get barely over half that. I'd love to have a modern powertrain and tranny rather than a carb and 3 speed.

Has anyone swapped an older cab onto a modern frame? Here in CA vehicles 1975 and older don't get smogged, which is a big advantage but I'd like the modern powertrain. I understand it won't be trivial but I'm wondering how possible it is.