The following site (see address below)should provide you with more information regarding the soldiers and passengers aboard the US Army Transport General Lyon.

http://home.att.net/~florencestockade/genlyon.htm

I know of no photos of the US Army Transport General Lyon. Another ship, a US Navy ship, which saw action on the Mississippi River and in the Gulf was the USS General Lyon (formerly the CSS DeSoto). Photos of this side-wheeler gunboat do exist, but it is not the ship which burned and sank off Cape Hatteras in late March 1865.

Regarding other information on your ancestor, you might try obtaining his military service records and pension application papers (possibly from his mother or wife) from the National Archives (NARA). Here's the address:

http://www.archives.gov/genealogy/military/civil-war/

Good luck.