IS it safe to re-torque the head bolts on an engine that has lots of miles on it (say 60k) to make up for any bolt streach that may have happened over the years? Wouldn't this increase compression and seal the gasket better?

 

I don't see any harm, but in the absence of any leaks I think I'd let well enough alone.

 

I personally wouldn't do it. Just replace the head gasket.