yup Dan pretty much mentioned the important thing with this engine....the chain. If its an 1985 then it pretty much has the double row chain so you just have to worry that it has been changed at proper intervals.
A freind of mine bought a 85 380se also......idle modulator (black box on top of firewall) went on him causing the car to idle near 2000rpm. This happened to me once. AC is almost gone on every 126 out there so its up to you to fix and I recommend a conversion which is what I did on mine......works beautifully and is the most powerful AC system I expeirenced in a car......so cold ur chest gets numb!
Just get the car inspected at Mercedes if your really interested!
my2cents