There may be others that I am not aware of, but the one source that I do know is a book written by LTC William Brophy, Ret. that is titled "Plans and Specifications of the LC Smith Shotgun". The book was published in 1981, and is now out of print. Used copies are sometimes available, but expensive.
I believe that there is enough information and drawings in the book for a skilled machinist to build a copy of an LC Smith gun.