I just had Springfield Armory install Trijicon night sights on my SA 1911-A1 milspec. They are excellent. I am highly enamored of night sights. I have had considerable, positive experience with them. I have them on my Kimber too. I recommend getting the Trijicons if you are going to use the pistol for self defense. They are strong and mine are quite visible, day or night. Of course they do not glow in the daylight. haha. I just posted some photos of them in the General Semi-auto forum under "New Night Sights". Take a look.
Colt might be able to install them for you. Springfield found them that needed no machining. They just tapped in. Good luck!