Justin,
welcome to the Stovebolt. That is a nice bunch of photos and it is a good looking project. I will comment on your frame question. It would not be wise to take the frame apart. Usually if something has to be removed, the new piece is mounted using bolts instead of rivets. Rivets however were used in the original design and they are better in that they fill the hole voids completely and they provide support in the shear axis.
