Low compression

How low?
What was the reading?
Did it come up any after doing a wet compression test, by squirting in a little bit of motor oil and repeating the test?
You may have to complete a leak down test to determine where the leak is. Could be the head gasket blown, bad piston rings, maybe even a broken ring, an exhaust or intake valve not seating due to a valve being bent or carbon buildup on the valve stem preventing the valve from seating.
What you do is rent, borrow or purchase a leak down tester, Place both pistons on number two at TDC, the remove the spark plug, apply the air pressure into the spark plug hole, remove the radiator cap, look for air bubbles, remove the oil fill cap on the valve cover, listen for air, listen for air out the tailpipe and listen for air back out the intake manifold and throttle body.
If air bubbles come up in the radiator then the head gasket is blown. If air is heard after removing the oil fill cap, either the head gasket is blown or the piston rings are worn or a broken ring. If out the tailpipe then an exhaust valve not seating and if back out the intake and throttle body, an intake valve not seating.