A little gap is normal but I saw yours and thought the same. The keys are wound up and you said it is lifted.
First off: What the hell is the year/make/model or are you under the false impression that ALL 2000 to 2006 GMT800's are the same?
Keep it stock and will save you money in the long run. I am not a fan of the lifted torsion bar/independent front suspensions.
Because of that gap, you may need new lower arm(s). Put some MOOG 81069 rear coil springs in it and some good Bilstein or KYB shocks on the rear and a set of matching on the front. I did the rear springs/shocks swap on my Z71 and could not be happier. Make the suspension and brakes primo and then do a Black Bear tune and you will get the seat of the pants feel you are looking for, especially if you do the Hellwig Performance bars, front and rear. See my build thread.
Like
@S33k3r said, make a list and do them one at a time. Also, may be not cost effective to fix and in the long run is gonna be better to buy another one, whatever that may be, and start from there.
You did not say where you live. Are you in a salt on the roads state? You don't but the truck came from one of those states?