Lift Help for 4x4 GMC

[SangerV]

Hey all I'm new at this and need some advise on correcting a mess. Previous owner lifted the front end by separating the shackle frame mount from the hanger and inserting (welding) 4" rectangular tube in between to install a brush bumper. I want to restore to original configuration with oem bumper. I have a new shackle and hanger and want to lift by the same amount with a block between springs and axle. Question is how tall a block to achieve the same lift ? 4" ? Thanks