Very interesting little buildings. Shingling them would require scaffolding if I was going to do it.
30 years ago old barns were being torn down to make picture frames. Art dealers were paying a fortune (at the time) for wood that would normally just be burned. My high school baseball team tore a couple of old barns down and sold the wood to raise funds for field improvements (with the permission of the owners, of course). 8^)
Some of the nicest boards you can get are the floor boards in the attic of an old farm house. They are perfectly flat and straight and generally were not nailed down, so no metal in them to wreck saw blades. Most times they are just pine but they are usually 12" wide and 12' to 16' long.