Trick with removing skins is go slow, use the widest pry tool possible and just work your way around.
After you get the doors apart have them chemically stripped.
All the repair parts available are pretty much junk in that they aren't 100% perfect match. I find the Rovers North ones have the crisp bends, which most others do not. If you don't mind that imperfection, either you or a local welder can section in the pieces. Then have the frames galvanized.
Prime everything while apart, then reskin the door frames. A good body hammer and dolly is a big help for this. Only hammer the inside edge!
1966 109 5 door wagon 300Tdi "spermaceti fueled"
1994 RRC LeWiB "ruining the air behind me"
All my troubles are Rover