I only did a 2" lift on my K10. I did not have problems with sway bar reaching mount points but did have issues with the bar approaching the axle at an angle witch causes it to bind as the front springs compress resulting in a stiffer ride. I installed OFF ROAD DESIGHNS sway bar disconnect kit...
That provides warm air to help the engine worm up in cold weather. Once the engine is wormed up a butterfly valve closes off that port allowing only cold air in. In Texas this feature probably isn't that critical unlike here in New England.
I replaced my 86 k10 upholstery in original factory mahogany from USA Ind. They do original factory colors but it would be for both parts of the seat and it takes several weeks because they make it themselves but do a nice job , fit great.