Vintage 44, can you post pics of the car, if the door jambs are gone I'm guessing the rest of the car is rough. You may need to straighten and brace the rest of it before starting on the doors.
If you look up 'rough' there will be a picture of my body (.. and of the car too). I'm sure you are spot on about having to brace a lot first. Wood Remover, your pics look to be very helpful. Looks like you brace with 1" x 1/2" instead of 1" x 1"? also I cannot detect any welds of the braces to the body. Super glue? LOL