Brace the cab is a good idea. 1/2 or 3/4" electrical conduit is what I used, put an x-brace in the door jamb, after the door is removed. May want to screw a 2x4 to the engine side of the firewall and then cut and fit a 2x4 from the bottom to the frame.
I would start with the outside lower cab first and drill out all of the spot welds, just drill out the panel to be removed not the under panel, up the door jamb, across the top and down the firewall/inner to outer cowl panel. Then replace it. Next the floor panel and inner cowl, you'll have more spotwelds to drill out here. Last would be the inner to outer cowl. Look at these [url=http://www.pbase.com/czechman/arightside][/url] it's a great photo log! Notice the "day 7" pic, this area will need a bunch of fitting.

....David