The control arm is a bolt-in. The torsion bars should be a bolt-in. Perfect time to replace ball joints, tie rod ends, Pitman arm, idler arm and bracket, front hubs/bearings, rag joint, CV shafts, brakes, etc. as needed.
Separating the torsion bar from the control arm has been a problem. I'm told--and have seen photos--that a 2-jaw gear puller works to push the torsion bar out of the control arm.
As said...be sure you really want stiffer torsion bars. When removing them from the donor vehicle, be sure to mark them front and rear, left and right. They need to be installed the same way they came off.
Get the "Z-height" correct BEFORE torquing the control arm bolts, if using bonded-rubber control arm bushings.