I suggest bolting both control arms in place and attaching the spindle to both. From memory:

If the bump stop is installed adjacent to the upper control arm, remove it- you're gong to need all the downward travel you can get to get the torsion bar into the lower control arm. Likewise remove the height-adjuster bolt on the lower control arm, if it is installed.

Grease the hole in he chassis mount that holds the back end of the torsion bar.

Determine correct orientation/side for your torsion bar. I forget whether you slide it in from the front side or the rear side of the chassis mount, but you can figure it out. Slide it in about halfway and install the grease boot.

Grease both ends of the torsion bar.

Put a floor jack under the spindle to hold it in position, and raise/lower it as needed. You can also tap on the "finger" of the height adjuster to rotate the socket where the torsion bar will go, but using the jack is probably easier.

Align the torsion bar to the lower control arm and tap it into place (hammer and wood block on back end). If it won't go, swear, check the elevation of the spindle, and retry.

Continue driving the torsion bar forward until the back end clears the retaining groove in the hole of the chassis mount. Install snap ring.

Stuff more grease around the torsion bar from the front side of the chassis mount and slide the boot over it.

Install bump stop and height adjuster bolt that you took out earlier.