we've had quite a few of them over the years and way back when we had our shop, put some on guns for customers...as for the 'factory' NO, they never made any as being shipped "original/new" ,BUT I'd bet the farm if ANY of Mr Rugers "friends" wanted 'adjustable sights' on one of their early, flat topped Single Sixes, he had them put on,just you would not be able to "substantiate" that with any 'service records, maybe a written correspondance by the original owner and the factory, say a letter to and from Mr Ruger.........
Our Wayne (Americal) here on the forum is one guy who loves to get,find, collect them, many of us have gotten some for Wayne over the years, he's been kinda quiet lately, hope his wife is feeling OK......
As for value, very 'subjective' mainly the gun and its value as to condition ( original finish of course) and the parts are what they are, aftermarket, and needs to be put back to "original" for the most part...me,I'd leave it be and shoot it , enjoy it for what it is and 'why' it is.....
Good luck, we need to "see" some pictures, love pictures.........