I have a 1990 K5 with a 6 inch lift. It drives kinda loose. What size lift will not change how it should drive stock? Thanks

If you want it to drive like stock I wouldn't want to go over a couple of inches.

Is there anything I can do to it to make the steering better the way it is?

Maybe take it to a good alignment shop and have them check all the suspension parts for wear. In addition a steering stabilizer may help. Ask your alignment shop about that.

I've got an 83 k5. Steering components are tight, went through a few steering gears before just accepting a have a 1/4 turn of play in the wheel. The frame where the box mounts is weak. I can watch mine flex, that's where my play is.

Yea had that beefed up so no flex. Its just super easy to steer. Really easy to over correct