I have just abut finished doing this on both sides of my truck (66 C10, I think its easier to take off the old rocker, then do the floor, then put the new rocker on and then address the cab floor supports if needed. I didn't brace the door, and it looks like everything will go back together just fine. I did mine with the cab on the frame. Pics here:

http://s140.photobucket.com/albums/r28/meld1234/Davids%20Truck/