I have one other thing to add, about the type of material that is used for the backing of the material. I let the upholster choose what type he liked, he chose this some kind of fiber board, is what it looked like. I was in Kansas and got caught in a thunder storm. I kept going but got soaked. I had asked the guy what to do if this ever happened. He said don't worry about it the leather will just dry out. Well I got to my hotel and water was running out of the door, it was a mess. I cleaned it up the best I could put the floor mats in my room, didn't use the car cover to give it plenty of air. The next morning to my surprise, the interior look like a mass of wavy leather. Everything had buckled, any flat surface was a mess, all because of the backing he put the material on. So this is why I insist on using metal on all panels. If you are interested in seeing a car with it done go to my thread, "One Way to build a '32 hyboy" there are several photo's. Once the panels are made I have them powder coated so they don't rust. I have been caught in the rain after that and have never had a problem since doing it that way. Just my 2 cents.
Ken