If you're not exclusively looking for carbines, there's Wilder's Mounted Rifles with their Spencer rifles at Chickamauga, Sept. 19th.-20th. 1863.
As for artwork:
The book "Don Troiani's Civil War", page 171, has a painting of a member of the 3rd. New Jersey Vol. Cav. levering a round into his Spencer carbine.
(The book "Don Troiani's Civil War Soldiers" contains no Spencer artwork, only the "fake news" on page 141 that Wilder's Mounted Rifles were armed with Henry rifles instead of Spencer rifles...)