The 1983 380 SEL did have the single row timing chain, which I have heard was a major defect in the design of the car. The single row chain would last about 30-40K miles. I own a 380 SEL, although it has been modified to the double row chain (which today is about a $3,500 to $4,000 job) Years ago MB picked up the tab, today you are on your own. They are a GREAT car (126 chassis) but you are better off looking for one in perfect condition.
I know you have already decided against buying the car but I thought the additional information would be helpful.