I suspect its Willard P Hall (1820-1882) not Wilbur. Hall was an attorney from St. Joseph MO and Lt. Governor 1861 - 1864.
James Allen was a Gamble appointee to Cass County Commision in 1863. His role in this document is unknown. He and his brother Andrew ran a store in Pleasant Hill, Cass Co and sold goods to Missouri and Union troops during the war.
See http://www.sos.mo.gov/archives/resources/findingaids/rg003-16.pdf
E.M Sloan was a councilman of Kansas City in 1862 by appointment. His daughter married a Dr Chew in Jackson Co. He relocated to St. Louis after the war likely due to a more favorable environment for a Unionist post war than Jackson Co. Sloan was a free stater and settled in Shawnee Co Kansas for awhile in 1849-1852.
History of Jackson Co MO. Union Historical Company 1881 (Its on Google books.) see also
http://files.usgwarchives.net/ks/shawnee/history/1905/historyo/chapteri5nms.txt
As you probably know Hugh Glenn was from Cass County as well. He played a role in the trial of Hamilton Finney of Harrisonville. Finney was former Cass Co clerk and accused of being a seccesionist.
John R.