I'm not sure that what I did is a true reflection of the chain stretch. My chain tensioner could have been weaker than yours at the time. My feeling was that, even if the chain was stretched, the new upper guides would have at least reduced the likelihood that it would jump a sprocket tooth and take out some valves.

Snaking a new chain in is a job that I know is beyond my mechanical abilities. I considered just changing the tensioner, which only involves having to pin the passenger side cams with the 6.5 mm pins (this prevents the chain from jumping the cam sprockets when the tensioner is removed). In any case, it's moot now, because that car is in the junkyard.

__________________
1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles