Hello Nicolas,
A "person" who is not able to remove the engine would be hardly able to perform a proper restoration process.
Removing the SL engine is not much different from removing other cars' engines.
Yes there is a Mercedes workshop manual available, which we here refer to as the "BBB" "
Big
Blue
Bock".
The original ones from those years are of antiquarian status and admit nice collector's value today.
There have been newer reproductions/reprints available from the Classic Center for many years... but I do not know whether these are still available today. Please contact them directly.
Otherwise: see the "Wanted to buy" section here or ebay or ...
Good luck!
Achim
(BBB only in German, sorry.... :'( )
