Easy to lower the rear. Not so easy to raise it. Old school method was to put longer shackles on the rear...but it would be quite easy to lower the front. Just add a block under the caster shim and put longer "U" bolts. Might work.
The front axle is below the spring pack and the rear is opposite so blocks won't lower the front. I had a similar stance and removed the shortest 2 leafs from the front which dropped the front bumper 1 1/2" and improved the ride too. Removing 1 might be enough to equalize the measurement in this case.
