The white outline rear sight blade and red ramp were available from the early 50s so it is possible. Is the windage adjustment screw crowned or does it have a flat head? If it is the former, it is evidence the original sight blade was replaced.
Kyle - Welcome to the Forum! As Doc had mentioned the "Red Ramp" sights were available for the .357 Magnums. S&W advertised the .357's as available with any Target sight. Below is a Pre-27 6" that lettered with "Red Ramp & WOR". Shipped 5-21-1968 to Edw K. Tryon Co. in Philidelphia, Pa.