2002 Ford Explorer Blown Engine

2002 Explorer 247000 miles, enigine starting making a ticking noise that increased in tempo with acceleration, I pulled off the road to check it out, after checking fluid levels, I tried to start it, but it would not crank over. The mechanic shop says it is a blown engine, primarily the timing chain causing the right side of motor to not work, and the engine has lost compression, he says the best recourse is to replace the motor for $5800. Can this engine be repaired, rebuilt, or because of the high mileage, is this the end of the road for this explorer's engine. Engine has had routine tune-ups, oil changes, no major repairs ever. First time for a major engine repair. Ever! What should I do?