I did this the other day and it was pretty easy to go from really lowered to slightly lowered. 1 turn of the spline equals about 2 1/4 inches lift/drop. Remember that the higher you want to raise the bus, the more you will have to compress the arm to slide it back into place along the spline to reassemble everything.
Once the bus is in the air and you've removed the spring plate covers things will get obvious.
Some advice - soak the spring plate cover bolts, on both sides of the bolt, with lots of a good quality release agent/penetrating oil. This doesn't include WD40! Something like a Comma penetrating oil, liquid wrench etc. I broke 2 bolts on one side and it was a nightmare to get the studs out so take your time.
Watch the brake pipe as it routes through the hub carrier on disassembly and refitting, it's easy to pinch/kink it.
Mark the position of your hub carriers to the spring plates with a scribe to ensure correct geometry when refitting.
Make sure that you can slacken all bolts on both sides of the bus before completing the first side. Nothing worse than having to reverse what you've done because the last bolt won't undo!
