You need an engine swap kit for a Chevelle body (since that is the closest body to mimic yours). You will also need a fuel tank with an in-tank high pressure fuel pump (you need at least 60 psi pressure to be able to regulate pressure in the fuel rails at 45 psi) or you can buy this pump and hope your tank is deep enough and in good enough condition to cut a hole in the top to try and fit this one in:
Leave the engine all EFI if you want to save money. In addition to a carburetor you would need an external distributor kit to control your ignition which is expensive and a carburetor manifold for your existing carb.
You can pull the engine from the pick-up with the 4L80 as a unit. Now go back and strip the truck of all wiring, wiper motor, lights, and master cylinder with associated anti-Skid brake computer (that huge monster with all of the brake lines and wires running to it off to the side of the number one cylinder). The computer(s) in this truck control everything (engine functions, transmission, brakes and fuel management). Now once you have swapped everything into your car you can drop the motor and transmission into your car body after bolting on motor mounts and then install your aftermarket 4L80 transmission cross-member.
Most kits include headers but if you want to piece together just mounts and oil pan (the truck pan will not fit, you will need an aftermarket Classic Car oil pan), and fuel pump. Luckily the full size car has enough room under the hood to clear a tall truck intake manifold (cast to make bottom end engine torque) and the high placement of the front drive accessories). If they don't fit your body then you will need the front drive off of a Cadillac VST car with an LS engine (they used a 6.2 liter version of the LS).
It took two experienced Chevrolet certified engine techs three days to swap an LS out of a modern car into a classic car using all of the available aftermarket parts back when I still had my shop. It wasn't cheap for the customer, but it was what he wanted. Performance wise it couldn't compete with a cheaper 496 BBC engine swap but he wanted EFI and modern engine issues like Active Fuel Management, and Variable Valve Management issues (he came back later to disable those features designed to improve mileage). Told him he couldn't have a thumpy cam because the computer couldn't handle it (such a sad face, when he finally figured out it was going to be as bad as I had described it before he began the engine swap).
Buy an aftermarket, fully programmable computer and add the cost of a dedicated laptop (full of tuning software) it will be a lot easier, but of course not cheaper. Add an American Automotive Wire LS-x engine harness and it is easier to install, but not cheaper. Use a n auxiliary front mounted sump tank and high pressure fuel pump; and retain your old tank and electric fuel pump, and you make it easier, but once again not cheaper (and more dangerous with a gas tank up front in case of a collision).
If you think this swap will be cheaper than buying a TBI SBC 350 out of an early 2000 pick-up and dropping it into your Impala you are very mistaken. This swap will cost you more than a BBC up grade to your 283, by quite a bit.