I have built several street rods in the past and have always thought of myself as fairly competant in doing pretty much anything to do with a street rod. WRONG!!!!!
I am building a 1937 Cadillac for my neighbor. This is a freeby for him. I talked him into buying the car and building it. He is pretty much not mechanically inclined, but is good at cleaning and hold parts for me. I have the suspension and drive train set up, welded and polished a complete stainless steel exhaust for the car, repaired all the rust areas with new metal and a complete frame off build. The car is sitting on all fours now so that I can square the doors and replace the wood in them with boxed tubing.
This is where the problem comes in . I have never replace the wood in these old cars with steel. I am a certified welder and a Jorneyman Machinist by trade. I can usually visualize how I want to do something and do it. I have come to a screeching halt at this point. I am trying to integrate a steel structure in the lower half of the door and leave the wood in the upper half. The wood is in there in such a way that it is going to be an extreme amount of work and time to replace it all, thus the idea of integrating the steel to the wood. I can't seem to find a good place to try and splice it. I feel it is a major possibility of doing damage to the door by trying to take all of the wood out. All of the rest of the wood in the car I have replace with no problem, such as the body mount rails and the structure and frame around the rear window.
I have spent about $60,000.00 of this guys money on this car and not charged him a dime. It will be one hellacious rod when I am done. It has the best of everything.
I guess this is a preview of what is coming for my car. I have a 1929 Buick and the wood is in really bad shape completely through out the car. I am going to have to build a complete inner structure in it. The wood for it can not be bought so I will build the structure with steel. This is a completely new area for me. I have done a search and found several posts where people are asking questions, but nothing indicating a how-to.
If anyone has some pointers please let me know.

Thanks, Ed