Hello I lived in Peoria all my life til 18 years ago, I do not ever remember Peoria being refered to as Ft Clark. There is some one at the Peoria Journal Star newspaper that does the history of Peoria, and he may have some information regarding the courthouse, I do not think he could help with family names. Look up PJStar.com and check the contact list for Bill Adams, Bill might be able to tell you about the courthouse. I do no that a new court house was built in the late 1950's or early 60"s I wish you luck Carol