I figured I would start by posting some pictures of the reason why I will be swapping cabs on this truck asap!
Here's some common rust in a typical place.
...and more on the other side, including the door, and below the lower hinge which worried me a bit.
This is probably the worst and would be the most difficult and time consuming to repair. It's rust on the firewall, and you can start to see the rust on the outer edge of the heater box, and inside the pasage for the heater.
The rocker panels, inner and outer, along with the floorboard, is rusted through. Much easier to just replace the cab than fight with all this rust!