Upside -- cheap.
Downside -- early 80's 380SL models had single row timing chain.
These chains need to be replaced more often, or upgraded to a double row unit ($$$). Some have already had this retrofit. Here's a procedure that anyone (even a novice) can use to check:
http://www.slack.net/~thundt/mercedes/timing_chain_380.htm
Here's a link that provides an overview article for all years of R107 SL production:
http://northernresource.com/mercedes/107.htm#ROAD_&_TRACK_-_March_1994