I have a 1968 Model 41 with the long slide and muzzle break and it has significant bluing wear on the slide and I'm thinking of sending it in to S&W for a new high luster blue. I know everyone tells you not to do it because it's not original anymore and will be worth less. This is my shooter model 41 as I have a mint in the box 5 inch inch and I shoot the c__p out of the 7 inch at the range. I'm not worried about resale as I don't plan on selling it and I for one have never admired guns with a ot of bluing loss so to me it's worth it.
If it were mine, I'd probably get it refinished. You have my permission to get it reblued. The bluing process has changed since 1968, but the new blue Smiths still look pretty nice.