Welcome to the Team Danil!
I would recommend a complete kit from some one like Ecklers :
or Energy Suspension's Moog replacement kit:
with a new upper front control arm shaft:
along with all new polyurethane bushings to replace the rotted out rubber ones:
Just be sure to add all of the optional parts. You will also really
need the motor and transmission mounts, as yours were recalled in the first ever safety recall of any product in history.
Be sure to specify the 1963-69 327 motor mount as you want the early style "short and wide" motor mount that measures 2 5/8 in. between the ears and 1 3/4 in. tall to the center of the through bolt hole part number 3-1120G for black or 3-1120R for red (all of the polyurethane parts are cast or machined out of red or black plastic, you have to pick a color).
If you want to get exotic after that and build road racer like performance for your impala you can find all of the components you need here:
Note they will sell you the quick turn steering gear box you need as well as the adjustable Panhard bar you will need if you want to lower your Impala.
This brings up the issue of lowered steering knuckles or lowered springs. Both will drop your car from it's stock ride height (maybe a half to an inch lower than you are now with tired sagging springs that are nearly a half century old). I recommend buying the springs directly from Eaton or Moog by calling up their customer engineer (these are the two companies that GM sourced for the springs originally used on your car; as they are designated OEM suppliers). You will need to have the weight of the car (preferably the four corner weight of the car using portable scales found in the trunk of every DOT officer or the shelf of your local rounddy-round racer) and a truthful
(you will have to live with the results) description
of how you want the car to handle as well as what ride height you want. They can then custom wind springs for your car. Dropped steering knuckles (spindle raised two inches) are the way to go to preserve your suspension travel, but they can interfere with wide rims as they bring the inner edge of the wheel closer to the suspension parts.
If you do buy lowering shocks you will now need shocks that are valved for the reduced suspension travel that you will you have (you should also retain the stock rubber bumper stops as you will be hitting them much more frequently on bumps and the plastic ones are stiffer. Bilstein can build a custom shock for you as can QA-1 and Ride-Tech. If you retain the stock shocks expect to be hitting and replacing the bump stop a lot if you drive your car much.