With all you went through and threw into your Jeep to try and correct your steering issues I fully trust your feedback.That list doesn’t include control arms. I would get your caster checked—I bet it’s too low. Mine is at around 7* and it’s great.
However, correct caster will help with wandering and overall feel but not dead spot (at least in my experience).
Honestly think it’s in the steering box itself and really nothing else we do will correct the dead spot. Seen the videos of people who did adjust their box and the dead spots go away. Just don’t want to be the guy that does this and gets too tight then boom, can’t steer a corner and crash.