Give me some time and I'll tickle these out for you. (I do people not units...)

Here is Bowen I suspect:

http://www.sos.mo.gov/Images/Archives/Military/s00727/s00727_1237.pdf

Elias Oldham Bowen Capt. Co K 8th MO Inf (Mitchells) appointed 12-23-1862.
Resigned Camp Bragg Arkansas Dec 1863. He also may have served initially as a private in Co I. He enlisted August 1862 in Barry Co Missouri.

There is a listing for an E. O. Bowen, First Lt, (then 3rd Lt.) in 6th Regiment Cavalry, Missouri State Guard (8th Division)

1850 Census shows him to be 19 (B abt 1831 in TN) living with parents John S and Elizabeth Bowen, dwelling number 256, occupation Farmer in District 5 Barry Co. MO

He married Miss Catherine Wallace in Barry Co MO on May 9th, 1869 at Mt Carmel Church of Barry Co. Thus apparently surviving the war.

Though I can't prove it's him, the 1880 census lists an EO Bowen with wife FC Bowen in Lamar TX.

John R.