Sounds like a good score BCDC,
There would be quite a few owners with similar stories I think. We've had numerous benzes in the family for many years.
Yes I think personally the M110 is a very underrated engine, runs very smoothly if a little noisy due to solid lifters, but that's OK.
The W116 too overall is a very robust car except for rust issues common to a lot of cars of the era, and are great to drive. I find they are quite agricultural compared to later models, but that's a good thing and all part of the experience.
Welcome to the world of W116 ownership, this forum is probably one of the best resources I'd have to say.
Tim