INstant center moving farther forward, bigger BITE, if it liked to lift em before, its going to want to lift em even more.
Coil bind, now that throws a differnt ball into the playing field. Increaseing rear squat, might enable that bite without pivoting the front end. Rather like the South-side bars did on the stock chasis stuff. Instead of lifting the front, it "DUG" the rear in. Allowing a little more squat before weight transfere, might prevent some of the harshness of the lift.
Could also add to the headache........ because as the rear squats, the instant center moves forward, even further. Its one of them catch 22 situations, where with the coils going solid, there was nothing for the car to do but PIVOT. But the pivot point was set, and you were comfortable.
With the added spring travel, the pivot point is moving, it might not lift the front tires at all.... allowing the rear to squat and absorb that engergy before a "pivot" is achieved. OR, with the now more mobile instant center, you might find the car likes to pick the tires up a little later, but is more difficult to control the amount of lift.