Fortunately, NCOWS isn't hamstrung with that particular ruling. As Books mentioned, the Laramie's rear sight is a virtual dead ringer for the 19th Century target sight used by S&W on the New Model No. 3. As it is correct to the period, it's OK for NCOWS.
Guess I fail to understand this (IMHO) hypocritical SASS ruling. SASS permits short-stroking rifles and revolvers, turning SAA barrels for windage, gun configurations that never existed until the late 20th Century and on and on ad infinitum, but relegate the Laramie's period correct rear sight to the "Modern" category. Makes no common sense to me.
SASS is a fine outfit, but that is a ridiculous decision from where I sit.