If it's making a banging or knocking noise then the rod bearings are gone. They can be replaced in the car but it's very, very difficult because you have to lift the motor to get the mount off so that you can get the pan off. Plan on spending a full weekend under the car. Even though you can replace the rod bearings, the crank is likely damaged, especially if you've been driving it with the noise. Because of that, the bearings won't last, and even then, because of the severe overheat it's extremely likely that the cylinder head is cracked and if it isn't already leaking coolant into the cylinders and oil it will soon be.
Sorry to say, but your best bet is to start looking for a replacement, either car or motor, because your existing motor is pretty much at the end of its useful life.