What do you want to do with the gun? Carry? Range toy, etc.
Is it a "Mil-Spec" or a "GI", if it's a GI, IIRC they are assembled in Brazil, not just the frames, and many of the small parts are of lower quality.
I would start with a high quality properly fitted and tuned extractor and forged slide stop.
I would look at having teh plunger tube staked(some ar ejust glued in)
Same with the grip screw bushings.
If it has the tiny USGI type sights, you'll need to look at replacing them. There are still some stake on tyep front sights out there, and some pretty good dovetail fit rear sights. OF all the money I spent on 1911's, milling for rear sights is probably the thing I would not do again. Plenty of take of dot types(I have handfull) or other "NM" & "retro" type sights. Check Brownells, or look around for some old school KIng, Wilson and MMC's, the 10-8 one is nice also.
I wouild probably just replace the fire control components, rather then do a trigger job. See what your smith says..if you wanna DIY look at the kits from Nowlin and Cylinder and Slide.
Grip selection is endless
If you go to a fitted beavertail you will need to address the hammer.
IIRC the Wilson Drop in was pretty nice and required only fitting the arm to the trigger bow.
Find a trigger length that you like, flat or curved..
I think it's better to do everything that interacts with the trigger at one time. Trigger, sear, disconnector,hammer, grip safety and thumb safety.
Springfield supposedly had some issues with the two piece barrel, but I'm not entirely sure about it. A fitted bushing is nice, or an entire barrel and bushing.
All depends on what you want to do and how much you wanna spend.
For reliability and durability, I'd look at the extractor and slide stop.
Bob