I am growing more convinced that the images from classiccmp/bitsavers above are just regular Unix v5/v6/v7 images, and not UNIX-11 for the smaller PDPs. I’ve been unable to boot them in SIMH. I have also been unable to boot them on simulated 11/45 or 11/70 machines, though, so perhaps I’m dong something wrong.
More study is warranted.
In the meantime, though, as seen in this other post,. I have many other things to occupy my time. I’ll revisit booting UNIX-11 once I have anything at all booting!