Thanks all.
I think I will do the initial repairs with the cab on the frame to ensure everything remains square. Inner/outer cowl, toe panels and front body mounts are all toast. Once I get the bulk of those done I will be more comfortable removing the cab, with some bracing in place. I can then rotate the cab to gain easy access to any other areas.
The good news is that there is a lot of good reference material out there for these repairs.