I found the sources for the second (2nd) and forth (4th) edition of the lisp machine manual. I did some hacks trying to convert them from biblio to text. The simplest thing turned out to be a sed script which generated texinfo.
Here's a quick hack to put the manual into texinfo and then html. It's got some issues, but it's a good start. If you want to improvement let me know and I'll put the sources up.