I know something you can do, instead of blocks to lift the rear, build your own set of stiffer leaf springs. It can be done for around 30 bucks, hit up the junkyard. I used a set of full size dodge leaf springs for their double spring clamps and extra strength of the full sized springs. I retained the bronco ii's eyelet spring so the springs fit like stock, just with about 5-6 inches of lift depending how much of each spring set you use. You'll probably need longer U-bolts to but they're cheap, and a strong C-clamp to get the springs apart safely. You rear end will have a whole lot less lean when turning and quick cornering, only down side is its a stiffer spring so speed bumps are felt a lot more when you rear axle goes over them compared to the front... I didn't care at all, the truck was lifted 6 inches and handled better than when it was stock height.
And also if you're using a body lift its probably worth it to just lose the height for better stability, body lift's are crap unless you're swapping engines too and need the room.