I have been on planning to build a few 1911's just never seem to get around to it. These are not as simple as AR15's. A very good understanding of parts interaction is needed for proper fit's and adjustments. Even many drop in parts require fitting.
I have done things like replaced and fit barrels and barrel bushings, installed ambi safeties, grip safeties and triggers. For me it has always been a lesson in patience. Something as simple as an ambi safety required a lot of slow fitting, drilling a small dimple for the detent.
There are two books you should get before attempting this.
JERRY KUHNHAUSEN THE COLT .45 AUTOMATIC JERRY KUHNHAUSEN THE U.S. M1911/M1911A1 PISTOLS A SHOP MANUAL