Sights and "etc."
Sights are easy. Yost makes a rear sight called the "Retro" that fits in the existing dovetail and has a .140" notch, slightly wider than the original. Medium tenon front sights can be added with no modification to the pistol.
The "etcetera" part can get into lots of money. Changing springs is quick and cheap, replace them all (main, recoil and sear) with Wolff. Ignition parts can be replaced with non-mim if it's an issue for you but they need to be fitted by a 'smith.
My advice to anyone considering modifying a 1911 is to shoot it a lot and make lists of things you want to change. Don't do anything on a whim, it costs too much money.