In alt.os.multics the availability of a pre-alpha state emulator of Multics/ge635 has been announced. You can see the code at https://sourceforge.net/projects/h6180/ or download it via:
svn checkout https://svn.code.sf.net/p/h6180/code/ h6180-codeThe author states that he is willing to work on or discuss the design, since it is in a very preliminary phase.