JVB,
The Master Materials List of the organization World War I Aeroplanes Inc. lists a number of Morane-Saulnier documents. While none of them is listed as pertaining specifically to the Model "L", I'd think that many of them would of value. An online version of the Master Materials list can be seen here:
http://www.ww1aeroplanesinc.org/docs...als%20list.htm
I recommend contacting publisher Leo Opdycke if you require specific information about what is in any of the materials listed.
I do some volunteering for WWI Aero, so let me know if I can be of assistance. I hope this helps.