Well, there was only one finish that came on the M-28, 4 & 6 " bbls, but you could order target triggers and hammers, along with target stocks. S&W made this to be a working man's gun, and would not alter it to look like a flagship M27. I have several of them. They are my favorites along with M15's.
I do swear though that they occasionally used M27 parts. I have a couple that have pretty highly polished cylinders.
If it were me, I would sell the gun. It has to be worth 500 or so, and then put the 300( guess) that you are going to pay to strip it and refinish it together, and for 800, you can get something nice and original. Just a thought.
I have no idea if this gun has sentiment, but if not, I would not refinish it, and if you did refinish it, I would not put a M27 type highly polished finish on it. I would stay with the original satin finish