I've done exactly what you are looking to do with a box blade: drop the scarifiers to tear up the grass - if you get the angle of the blade right, the scarifiers will dig in, and the blade will skim the turf right off the top. Drag that aside, then go back and start dragging the soil. The scarifiers will help loosen up the soil, making it easier to move it. As you approach the finish grade, raise the scarifiers and use the blade alone to smooth things out.
The real key to using a box blade effectively is learning to get the angle set right (by adjusting the top link length). There is no substitute for just getting on and practicing with this. Things go much quicker if you add a hydraulic top link and side link to your 3 Pt hitch. That allows adjusting the top link & side links on the fly, from the seat of your tractor. Adding that is not cheap, if you don't already have two sets of rear remotes. (If you have one rear remote, I'd recommend using it for the top link).
The other big tip for using a box blade is to do it when your soil conditions are right. Too wet, and you just have a sloppy mess. If it's too dry (hard as rock), you may have difficulty skimming off the turf and getting th eblade to dig in properly.