The 23rd has a monument/marker at Shiloh as well, while not specific to any company I figured I would put this here. I just found this minutes before this post and am ecstatic! I've been researching the 23rd for months and just happened to stumble across this gem. Hope you enjoy!
Found on:
http://shilohnick.blogspot.com/2008/06/ with the text:
"On back of monument:
23d Infantry
Commanded by Col. William L. Sanderson
From Stony Lonesome, April 6, 1862, at 12 m., this regiment marched to a point near Clear Creek; countermarched there, it reached battlefield, via Savannah road, 7.30 p.m. April 7th, formed line of battle at sunrise, engaged the enemy, drove him to this position, where two hours of desperate fighting occurred. Enemy retreated, followed by this regiment until nightfall. Casualties--killed, 7 men; wounded, 1 officer and 34 men; missing, 1 man; total, 43."
PS: My 3x Great Grandfather was in the 23rd Indiana. Patrick DeWitt