Are you looking to build a match-grade pistol or just a good solid daily shooter?
If you want a very decent quality drop-in/semi-drop-in kit, check out the Nowlin kits.
I've used the Commander kit on a Springfield and the ProMatch kit on a Taurus PT1911 with good results. Both of them turned out nice enough that I didn't do any fine-tuning or fitting on them other than fitting the safety. (I installed new safetys on both of these pistols since I'm a southpaw and needed an ambi).
I've never used the C&S kits. I'm not impressed with their safety levers though so I really haven't used any of their other parts.
Several years ago, I pieced together a new action for a series-70 Colt with assorted individual parts. Wilson, Clark, etc.
That was my first 1911 job so I spent a LOT of time being mentored through it by a local smith and I botched a couple parts until I got em right. It turned out just fine in the end but was a lot of hand-fitting. Without the proper jigs/fixtures it's pretty tricky, if not impossible, to fit oversize parts to your gun.
Helix is spot on about it not being a real easy job to get a match-quality trigger.