Ford Repair: Timing chain, timing chain, conservative side

Question
I am in the process of redoing the heads on my 92Explorer(165K miles).  Up until the thermostat stuck and blew the lower manifold gasket, it had been running fine.  #6 intake valve is leaking, though.  My question is, should I go ahead and pull the front cover(front seal is probably leaky) and change the timing chain?  Not sure how long these wear, and I would prefer to do it while it is apart now, than to have to get into it again later.  A little expert advice would be appreciated.  Thanks

Answer
Dean-

  There really isn't a magic number for timing chain wear.  I've heard some shops quote 50K-75K miles, but I think that's a bit on the conservative side.  But at 165K miles I'd say it's probably a good idea to change it out while you have the chance rather than risking it stretching.  Hope this helps.

Steve