The front sight on your gun would have been a plain half moon, not ramped like the one in your photo. In the book, it's described as "a round blade front sight." I don't have a photo for you, but you should be able to find one out there somewhere.
The book also says that the grips would have been "hard rubber or walnut stocks, with a [raised, uncheckered] diamond around the screw escutcheon and gold S&W monograms." I think the "monograms" referred to are the medallions with the company logo that are inset into the rounded top of the grips. So, those would also differ from the grips in your photo.
I don't know what the "notched" business is on the grips that Numrich is listing. I'd recommend that you visit the S&W Forum and check out their classifieds - you might find what you're looking for, or you could post a WTB with the vintage of the gun and indicate you're looking for original grips and see what turns up.
ETA: This thread
has photos showing the correct front sight and grips for your gun.
Your Model 28 dates from between 1969 (starting at N1) and 1972 (ending at N99999). The 686 is from 1985.