2004 Dodge Srt-4 Overheating, won't start

Hi, I have a 2004 Dodge Neon SRT4. I tested the cylinders, and only one of four was holding compression. I have called, and talked to a lot of people, and keep getting told different things. I've been told that its either the Head Gasket, Catastrophic failure, Piston and or piston rings, or possibly the radiator. It was having major over heating problems. (Couldn't drive for more then 10 minuets without it over heating.) It would occasionally have trouble starting, and when it did, it would blow thick white smoke out of the tail pipes.