The .278 height red insert blade I put on my 60-15 (see my recent thread in this section
https://smith-wessonforum.com/s-w-revolvers-1980-present/231822-my-favorite-woods-gun-has-new-sights.html) is available directly from Smith and Wesson by simply calling them. It should fit your revolver, although the height may be different than the sight already on your gun. They may have other height red-insert blades available, but it didn't seem so in my last phone call to them. If the height is not correct for your gun, you may have to change the slide height in your rear sight.
The new front sight blades are NOT drilled for the pin, so you must do this yourself. It is not a big deal (I did mine CAREFULLY with a hand drill). The tiny drill bit needed is available from Brownell's. Details on blade installation can be found by searching in the gunsmithing section of this forum.