http://history-sites.com/research/index.html
A capsule history of the 1st. Miss. Infantry is available at this site
http://mississippiscv.org/MS_Units/1st_MS_INF.htm
and it does appear he has the wrong military marker.
http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GSln=Scott&GScid=54296&GRid=26524994&