I'm not entirely sure if I should go ahead upgrade the bearings, or replace with ac delco gold inner and outer bearings.
Why replace the bearings if they aren't showing signs of wear?
My expectation is that they're fine...once you clean and repack 'em with proper wheel-bearing grease. There's about a thousand choices for wheel bearing grease, and pretty-much any one of them would be fine. NLGI #2 (common as dirt) with a rating of "GC" (also common as dirt). Most automotive greases will be NLGI #2, and dual-rated for chassis grease and wheel bearing grease: LB/GC.
I'll have to check the control arm bushings, I was thinking of poly bushings but I remember keeping a can of wd40 to stop the squeaks, though at 168k they should be ok.
Poly bushings need GREASE, not "WD40". No wonder you had trouble with them squeaking. The grease supplied with them is the stickiest grease I've ever seen. Regular automotive chassis grease is probably not acceptable, either.
I'd expect the upper bushings are totally wiped at that mileage and age. Lower bushings may/may not be usable. The problem with Poly bushings on GMT400s is that they include the steel inner sleeve for the lower bushings, but not for the upper bushings. I had to fabricate my own steel sleeves for the upper bushings because the originals were TOTALLY shot.
Photo 1. The "fat" steel sleeve is what both of them looked like before I polished-off all the rust. The "skinny" steel sleeve is what was left after loose rust was removed. I spent hours making the new sleeves, because I don't have a lathe. Had to do it all "by hand".
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Photo 2. The expansion in diameter of the inner sleeve due to rust causes stress to the rubber, leading to the demise of the control arm bushings.
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An aftermarket upper control arm pair avoids the bushing and ball-joint issue. No idea if they're available for 2WD, but they are for 4WD including the 8-lug version.
I'll probably go with Mevotech swap bar end links and swap bar bushings just because they are cheap and I'm already replacing stuff.
Swap bar? Do you mean "sway bar"?
Is there anything else I should look for besides a gear box, power steering cooler? I am running what I believe are stock sized tires with stock wheels.
SOME GMT400s have a horizontal "shock absorber" on the steering linkage. If yours does, make sure it's in good condition. If not, consider installing one if you're on rough roads or off-road.