I did the same job not too long ago, but the difference was not significant enough to me. The timing chain job was past due in my case, with the car at 235k+ miles at the time the chain was replaced.

http://www.peachparts.com/shopforum/diesel-discussion/328442-w123-timing-chain-replacement-photo-references.html

When I got my car in 2004 it already had a 3.69 differential. So it's been screaming its guts out at highway speeds until 2008 when I was able to source the correct 3.07. I wasn't able to check the difference between the chains though.