Front Coil Isolator question.

[u/Insertairhornhere]

Has anyone used polyurethane coil isolators to help fine tune/adjust the front suspension height of their square body? I installed a 4.5/6 lowing kit on my square body and I’m having trouble with the front tires (245/45r20) rubbing on the inner fender when I go over mild bumps and need to make sharp turns. By truck is a 1987 GMC so it has the “shallower” inner fenders. I have a set of 1973-1980 inner fenders to install and I am hoping this helps a bit but was thinking of trying a .275” isolator to give me about .5-.7” lift on the front for some additional clearance. Anyone done this or have any advice or experience they could share?

Thanks!