If the pistol is untouched you have just a stock dovetail. BoMar required (they are out of buisiness now) some fairly extensive milling of the slide. Novak will require less but neither is a 'drop in'. Brownell's did a 1911 build up and if you look there I think they have a picture of the milling required for a BoMar.
In the Bomar cut the back of the slide is milled flat and the dovetail is milled below the flat. Midway carries a Bomar cut sight by Champion which will fit a Bomar cut. Caspian Arms carries a line of sights which have a Bomar type cut. Their ghost ring sights are excellent if you have older eyes.
Springfield 1911 question
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