There should be 2 nuts on the top of the cross-member. The second one serves as a jam nut. Use 2 wrenches and loosen the top nut several turns so it's out of the way. Then you can hold the lower nut with a wrench while you turn the bolt. When you have it where you want it, tighten the top nut against the lower nut.

As long as there is a little space between the upper bumpstop and the control arm you're ok. The FSM calls for specific measurements from the lower bumpstop to the frame horn but that's a tough way to measure. Use a 5/16" or 3/8" bolt and tighten the left side until the bolt will just clear between the upper bumpstop and the control arm - then do the same thing on the passenger side. You'll find that the left side has now changed, so lower it until you can clear the bolt again and recheck the passenger side. I like to set mine up so the driver side is 1/4" higher than the passenger side to allow for driver weight loading when there's no passenger.

If you still need additional height you can shave the bumpstops a little. An easy way to shave them equally and with a good cut is to first remove them from the control arms, screw them to a board and run them through a table saw with the saw fence as a guide - then they'll all be the same.

After you have the height adjusted, you'll need to check the front end for correct camber setting because any change in the torsion bars changes the camber.

Frank