Your chassis is not looking like it is flexing. It looks good.
The suspension looks like it does have a little bit of a barrel roll in it, but not bad. By looking at it I would say that your bottom bars are close to level currently.
I could guess that moving your I.C down slightly with bottom and top bar down one hole and a loosening of the shock extension dampening might help and you still have good traction by looking at the pics. The rear suspension is acting too radical in the rear.
Anti-Roll bars are often used as a crutch to band-aid a lack of suspension adjusting capability either in the car but usually in the chassis adjuster's brain. They are helpful in fine tuneing a barrel roll condition though.
A 4 Link is not a Ladder Bar and does not work the chassis the same way. The only time a 4 Lnk rear suspension bar angle is the same, right to left is when you are sitting at rest with no torque force applied. As soon as you start the launch the right side and the left side are independent from each other in what happens with bar angles and leverages. I promise you that when you get your front to rise left to right evenly that you will slow the car down.
If the car is launching straigt and true do not adjust any sort of a pre-laod in the bars or with springs.
The way I see it is you are not radically lifting the left front tire as compared to the right front. It is an illusion you see. What is happening is the right rear tire is being pulled up in the fender by bar angle with torque applied and the chassis is stiff enough so the left front is rising more. At the same time the left rear tire is being pushed downward away from the fender by the change in bar angles with torque applied.
That is nothing but the laws of physics in motion working the way it should. by adjusting the bottom bar angle to be lower in the front you are counteracting some of the right to left difference in angles while launching.
If you know what you are doing you can do an assemetric left to right suspension adjutment but be careful. At times what seems to be good for the launch can throw you at the high end when torque unloads and you are trying to slow down with a car pulling to the side. It is all in the finese of making tiny adjustments and knowing in advance what you adjust will do from one end to the other.
Ed