I agree with Pork and wouldn't push your luck if it's past 150k miles. The V8's seem to fare better than the L6's b/c the larger engine isn't stressed as much during take-off or hard acceleration.

Like Pork I don't believe it's worth the gamble. The cost of the chain replacement (& related components) is so much more manageable than the cost of the 2-bank head job (and maybe the cost of a punctured piston too).