There are a few reasons that these engines tick. Usually, it is not a sign of impending demise.

#1 is the timing tensioner. Many a mechanic would diagnose a rod bearing for the sound, but it is the tensioner.

#2 if it is just a lighter tick, it is probably the way the oil flows through the upper end of the valve train. Common, no real damage, but there are several methods of dealing with or treating it.

Either #1 or #2 can be found by searching. It may save you the headache (and cost) of an engine swap.

Michael