Bob,
Glad you are happy with lens. I also have a 4A, and would certainly go with the reversed recessed lensboard option. Even though this is a big lens, these cameras were built and designed for much larger. I use a 350mm f/3.5 lens on mine, a 12lb beast which no other camera could carry.
If you use the original studio stand, and the wooden shims around the sides of the center pole are in good shape (if not, they are easily to replace), then you don't really need to worry about secondary support.
Looking forward to more 8x10 pictures of your cat!
jason