My suggestion is to forget trying to make the front come up level. You have a 4 link not a ladder bar car. Ecah side of the rear suspension is operating independently to the other. It is likley the left front is coming up because the right rear is pulling up into the fender. When one corner does an action the opposite corner needs to be able to react and not be bound.
The top 4 link chassis minds do the adjusting on the 4 link on NHRA Pro Stockers. Do you ever see them launch with both front tires up the same amount? They could if it were better. They ahve double adjustable 4 links with bar adjust capanbility and even bracket up and down adjust capability. They have the best in anti-roll bars and shocks. They intentionally allow the suspension to work as it should to move the car out quicker.
You adjust rear pre-laod because a car is driving to one side during launch or first part of track acceleration. Adjusting pre-laod to get the car to rise level can be done but will bind the rear suspension movement and will also possibly cause the car to drive to the left. It will also slow you down if none of the other negatives show up.
If you have an anti-roll bar adjsut it to be neutral with driver weight in car. That is astarting place. Do not adjust anti-roll bar to make car launch level.
Ed