Is it such a big deal?

Ok so I have a similar question. I've got an 01 ram that has rust in a cab corner, passenger rocker, drivers floor pan, over the rear drivers wheel and 3 of the doors will need to be replaced. So i could either replace all that or I can get a clean rust free truck and swap on the entire cab (including the interior since it's the same as mine) and the bed onto my chassis, would that be considered a rebody and wrong? If you roll a truck, they put on another cab. If the bed is damaged they put on a different bed. The truck already has a rebuilt title and had some shoddy repairs done.