How is the bump steer with that setup?
There is none. It drives very well. I am looking forward to getting it on the trail in a couple of weeks.
Unfortunately, the geometry of that steering design creates bump steer. Here is why:
In a live axle positioned with a panhard (track) bar, as the front suspension cycles the axle moves side to side along the arc created at the axle side of the panhard bar. At the same time, the steering knuckle moves side to side along the arc created at the axle side of the drag link.
When the axle cycles up and down, if the two arcs are identical the axle and the knuckle move side to side at the exact same rate, and the wheels continue to point in the direction of travel. If the two arcs are not identical, the steering knuckle moves at a different rate relative to the axle, causing the wheels to deviate from the direction of travel. This is bump steer.
The easiest way to make these arcs identical (and the easiest way to understand it - see my stock comment below) is to have the track bar and the drag link be the exact same length, and parallel to one another. This way, during cycling the axle and the knuckle move side to side at the exact same rate, and the wheels continue to point in the direction of travel - meaning no bump steer.
Here is your setup - the red lines indicating the position of the track bar and the drag link. They are neither the same length, nor close to being parallel.
Now picture what happens when the axle cycles up and down. Because of the different arcs created by the panhard bar and the drag link, the steering knuckle will move relative to the axle and deviate from the direction of travel. This is the reason crossover steering does not work well in the TJ when using a panhard bar in the stock location. It takes surprisingly little difference in these arcs to create bump steer.
Now to complicate it just a bit, if you look closely at the stock TJ inverted Y setup, I believe the drag link and the track bar are neither the exact same length, nor perfectly parallel (it's been quite a while since I've seen a stock setup, so working from memory). However, they are engineered in such a way that the axle side arcs created by each are identical within the range of travel of the stock TJ - and therefore no bump steer.
A very easy way to identify if you have bump steer (other than noticing the effects) is to drive straight over a speed bump with your hands off of the wheel. If the steering wheel moves at all as the front suspension cycles, you have bump steer.
......But yeah do that,rivets are alot more attractive 
