Take this with a grain of salt, but since the parts are mostly cast/MIM (frame and slide), then things like tightening the slide to frame are not going to hold up long. On the FCG, again MIM parts, so will not hold a trigger job long as well.

Really, if you are going to build a race 1911, then you want at forged frame slide, then from there start fitting parts.

So on that note, unless the barrel is just beyond sloppy in the slide and the rifling looks/groups like crap, just replacing the barrel bushing to a fitted NM type, and changing out the barrel link to one that actually fits will put you leaps and bounds in the right direction you want to go instead.

EGW has some gunsmith fit barrel bushing that will fit the bill nicely, and regarding barrel links only a few dollars, all to get the existing barrel to lock up like a vault in the slide.

As for NM barrels if you need to go the extra step, I run Kart barrel when rusting is not going to be problem, then Barsto in SS when rusting is a concern.

SA had forged frames and slide, plus does not have the 80 series firing pin block that most current 1911 have.

Also, if you can find a Norinco 1911 on the cheap, they are great builders as well since both frame and slides are forged and hardened very hard as well. Just keep in mind that you will need carbine end mills and carbine dove tail cutters to work over the slide for adjustable sights and such on those parts.