The front sight on my .500 PC Hunter is a dovetail. I had to use a Baughman rifle sight to get a higher front sight. The quick change front sight on the .357 is a Weigand sight blade. Weigand's website has black serrated ramps, .250" high. You can put a dab of paint on it or look in Brownell's catalog.
Gun sight Interchangeable blade by Weigand
HiViz front sight from Brownell's
S&W CLASSIC, PERFORMANCE CENTER & DX MODELS OVERMOLDED SIGHTS - Brownells
Brownell's has a bunch of stuff. You can look through their catalog or call them.