Featured Technical Is this ‘63 Impala too high

Thought '64 was the first year of the Thrift Six, mea culpa.

Do you have the part number or measure the spring free height and wire diameter to confirm?

Spring clocking is critical.
On front LCA spring pocket there are usually two holes, end of the tangential end should cover one hole, not both. If it covers both it can bind the spring up.

On rear pigtailed end usually has to point a certain way either towards the D side or Pside. Can't just slap them in any direction.

Not only is it important to tighten suspension when properly laden, but one must also verify the suspension is not bound up beforehand.
After the car is back on the ground, roll it forward and backwards a few feet. Jounce the car a bit, nothing to wild, just want to get the car settled. Roll it back and forth and it should be pretty well settled.
Tires will keep the suspension jacked if car is not rolled after lowered to ground.

Those little teeth on bushing ends can grab, and if the old indents are catching on the new bushing crush sleeve teeth, it can hang up the suspension.

Leave the sway bar disconnected as well as shocks. Some gas charged shocks can lift the car if all the pivot bolts are loose. And older non-charged shocks can also be very stiff and not allow the suspension to settle evenly.

IIRC rear lower shock mounts
is also the same bolt for the axle side of the lower control arms on X-frame cars. I don't recall if the actual shock is used to aid in clocking this stud-bolt, or if it is designed in a way it can only go in one way.

A note on spring ends.
I agree, replacement springs that are not closed and ground, like factory, seems cheap and lazy. Open end is most likely done for speed and cost cutting at the factory. Less material is wasted, can make a single long coil and then cut it into however many pieces are needed.