Thanks to all for the comments.
With the long wait for letters, I'll have to go with what can be seen or logically inferred from what is there in front of me.
It's a pawn shop situation, so I can't take it apart and check numbers, letters, etc.

I think it's non-factory nickle because it just isn't up to S&W quality. (I have several other original nickle plated S&W's that look noticeably better.) I should have looked for the "B" in the shroud but did not. I was so surprised to see it there that I don't think my wits were fully with me.
Concerning the rear sight's originality, I'm a mechanical engineer who teaches manufacturing processes, so I think the sights (especially rear) are factory-done based on the quality of the machine work. No bubba/hacksaw action here. It could be a *really* good gunsmith, however, so I concede that there is a chance that it may not be "factory" (pending a numbers check).
However, to the best of my recollection the sights do look like the ones pictured above.

I understand the comments on investment/appreciation.
However, since I'm old enough that everything I have is paid for and I have no kids, anything I leave to my nephew (who has a good job and doesn't need the money) will be a "bonus" when I kick the bucket.

Also, I tend to buy guns based on their historical/technical aspects as opposed to pure "condition" considerations.
I think the experts' consensus so far is that the decision to buy or not is marginal. I would not be crazy either way.
(I may be swayed by the fact that when I got home and checked the mail I had a $500 check from a local utility, re-paying me for a mistaken over-payment by their automatic payment system.)
I'll sleep on it, but right now I think I'll go back tomorrow and have a second look and if I don't see anything about it that looks any worse than what I have already seen, I will likely get it.
Thanks again!