Index the bar to the a-arm, and to the chassis with a paint marker. The arm has a score mark on it already. Disconnect the shocks, separate the lower ball joint. Use a block of wood under the upper control arm to lift the spindle out of the way. Use a big prybar, and dead weight ( I use JungleJustice sometimes) and pry the arm down. Remove the bolts. Knock off the a a-arm. Clean and anti- seize the splines and socket in the arm. knock out the torsion bar from the rear. Clean and lube. Reassemble without the bolts. With the stock bars, a change of ONE SPLINE AT EACH END will lower the vehicle approx one tenth of an inch.
(Measure your ride heights at the fenders before hand. Determine how much you want to lower.)
Want to lower the front 1.5"? Go 15 splines at each end from your marks. I think the gain with 27mm bars is about 0.7" per spline. With stock bars, you can support the arm with a jack, and carefully pull the bar aft out of the chassis and arm, feel the splines engage, pull out, back in counting the teeth.