Don, I'm not really sure where you came up with a figure of less than $1000 to do the double row timing chain coversion.
This is a 107 SL, which means to do the conversion you either have to pull the engine and set it on stands, or drop the front suspension and subframe of the car and work from underneath.
To take the timing chest off, you have to remove the oil pan.
A SL has a one piece oil pan, so there are NO short cuts.
This is a job where you want to use MB parts only.
List on the MB parts is right at $1000. Pro MB labor is $100 per hour for the most part, and book time for this job is 26 to 27 hours for a pro. That's how I came up with $3500 for the conversion.

You *could* just replace the single chain and sprockets for around $1000. In my humble opinion this is a HUGE mistake.
I think it is absolutely necessary to convert the single row timing chain on the 380 engine to a double row. Single rows can snap without warning at any time. Even new chains and sprockets will fail catastrophically and suddenly.
On Sedans, you can leave the engine in place to do the conversion, but it will still run around $2500.
If you hear chain rattle on cold start up, TOW the car to a shop for the conversion so as to save an engine rebuild.

A good DIYer, with knowledge, skills and pro type tools could probably do this conversion in around 40 to 50 hours. But time constraints aside, it's one of those jobs best left to a pro.

There were rumors that MB did a brief factory unannounced recall
on the early 380's if the customer complained about the single row. It's said that MB did SOME of these conversions at no cost, under warranty. Why would they do this if the single row was sufficient? Needless to say, this practice was discontinued after a short amount of time. ($$$$)


Regards, Blitzen