The problem I see, we don't know the ops background/ if he is skilled in using lathes and mills to begin with.

If we take a 1911 build using all smith fitted needed forged parts, them the break down is such.

Fitting the slide to the frame, and then any milling needed to the frame and slide as well.  Hence checkering, sight cuts, and even flat topping and french railing the slide to take it to the next step.  Also, you have to add in finishing of the parts, hence bluing and/or bead blasting as well.

Once this has been completed, then Fitting the barrel bushing and barrel to the slide, them mating them to the frame. Next comes fitting the FCG parts, including a trigger job on the sear and hammer.  Also, depending on the build, may have a ramp well that has to be fitted and blended in as well.

With a mill and lathe to reduce a lot of rough  needed hand fitting work, it about a half days work to turn out a custom 1911, while if you are doing all this work by hand, days instead, and after you know what your doing to begin with.

On the other hand, if all pre-fitted parts, then min fitting needed, and should take about 20 mins to put the pistol together instead.

To bottom line it, what expectations do you have for the final 1911, and what details do you want on the pistol as well.  Baer make great forged slide and frames, but they require a lot of work to just fit the slide to the frame to begin with.  On the other hand, Springfeild armory makes forged frames (Imbel really) and slides as well, but you spend more time peening the slide to get it to fit the frame tightly isntead.

As for MIM frames and slide (and even parts for that matter), not for a fitted pistol, since you only going to get about half the round count of the MIM parts before you have to go back and rework the pistol to tighten it all back up to get it to shoot tight again.