We did this in my brothers 22 Buick Roadster body and I may have a few photos and will check. What we did was not try to duplicate the look or shape of the original wood at all, we simply made metal pieces that would do the same job, which is two totally different things. We used 1" tubing for instance around the back of the body behind the seat. The wood that went here was something like a 2x3 curved piece. So we bent the tubing over a jig and welded it to the lip of the body. The door jambs were made of 1/8" thick 2x2 angle iron. With one side of the angle simply cut and ground to fit the curvature of the body. So the inside of the door was flat, the door wood was replaced the same way of course. 1" tubing across under the dash board which we made from scratch looking just like the original. 1" tubing ran around the bottom of the body with some cross braces and it worked out like a charm. The doors are solid as rocks, original (repro) hinges with single side "Bear claw" latches. We cut the hole out for the hinge to sit in then simply backed the hole with 1/8" flat stock so the hinge was recessed in just like it sat in a routed out hole in the wood.
So that is how we did it, I have replaced wood in a couple Model A bodies, same way.
But the slickest I have ever seen was a 36 Chevy four door sedan I worked on one time 35 years ago (I painted it). This dude had replaced all the wood with thin sheetmetal (16 gauge or so) made to look like the pieces of wood! It was friggin amazing and a work of art. He literally took the pieces of wood and duplicated the shape in a metal "box" like structure. He did this with large holes punched in the metal looking like the inside of a friggin WWII war bird.
It was slick.
So you could do it either way, doing it the way this guy did is in a way easier, it would just take longer. You simply have to duplicate what you have right in front of you. no re-engineering. The way we did it was quicker, did the exact same thing but isn't nearly as pretty. It does look pretty much like what they would have done if it had used metal from the beginning, nothing special. That 36 Chevy looked like friggin art and it was a shame to cover it with the upholstery.
One of the most important things of course is that the body is in it's proper shape before you do any kind of final welding. The doors are a mutha on those cars and get all twisted out of shape over the years. So the shape that it is now with the wood is likely not what it needs to be.
Anyway, there is some ideas for you to mull around until you get some more info and make an educated decision on how you want to go about it.