Bad compression is almost always caused by one of three things. 1. Burned valve or bad valve seat 2. Broken or worn piston rings 3. Blown head gasket, scored or cracked cylinder wall or cracked cylinder head.
You seem to have eliminated a blown head gasket, cracks in the block or head, so that leaves problems with either valves or rings. Either of those means taking the engine apart to fix it. If it's burning a lot of oil, that sounds more like rings than valves. The good news is that since you need to take the radiator out to pull the engine, you can get the radiator leak fixed at the same time.
