Ifs axles are 1.5" wider per side so thats a total of 3".  Id skip the chevy's and get a set of bronco II's or ranger springs for the rear.  They dont have the added length in the rear to catch on everything and they are cheaper cause not everyone uses them and there are more of them in the yards to choose from.  For the front just use your rears and longer shackles.  Way cheaper approach to mass flex.   And as you know Im all about the cheap!