fitting efi engine into a Carburetor car

You can't easily use the 2.0 tank as the carburettor fuel line isn't large enough bore to reliably drive the injection pump. You also need a return line which most capris don't have. The swirl pot is one of two things - in a "proper" injection tank it is a small well which sits around the pickup pipe to prevent air entering the line as the fuel swills around in the tank (this isn't a problem with carbs), or it is a small external tank fed from the main tank with a low pressure pump. The injection pump then pulls from this tank and its return line goes in too, works well as long as it properly sited, but its extra complexity that I don't like much.

Now, siting... NEVER put a fuel pump in the cabin or boot on a road car. Just don't. It needs to be outside of the car, like the standard 2.8 pump arrangement alongside the tank or inside the tank like most moderns. Putting the pump in the tank is fairly involved and requires welding on the tank, so it's best to start with a new one...

If I was you, I would be looking to replicate the factory setup from the 2.8, maybe even try to find another 2.8 tank?