You need a lot more rear rise, then you need to maintain the rise some, radials need to be hit hard / planted to the pavement to work best. Are they radial slicks or radial streets ? Can you raise the front eye in the ladder bar ?
My experience is with Caltracs and radial slicks, so no expert at all with ladder bars, but we were hitting a bias ply way to hard with our set up, despite the theoretically least aggressive settings. Changed over to radials and instantly picked up across the ticket. We also have Menscer Radial valved rears, we switched to Santhuff fronts from menscer / afco. The Santhuffs are a superior unit.
Below is a pic from the last pass of the season, basically testing stuff with new 3.73 gears in the dana. We run around 20lbs in the rears, though we have gone as high as 22lb on a hotter track. We've been 1.32 putting the fronts down before the 60ft, and 1.39 on the backs. car weighs over 4000lb w/d.