I'd look at the 7th Ed. sources and the install process to see what
7th Ed. is expecting to load onto.
You need to rewrite things. There is no way you can get something written
for the Unibus, and large memory, work on a q-bus without rewriting some
stuff.
... and later by this:
Not the 'official' thing but a good point to begin. In fact is what I'm
preparing for my PDP-11/23 PLUS
Regards
Sergio