FWIW, I can confirm that the 730 console tapes are in RT11 format, as are
the 750's. DEC standardized on that format for console media, even though
there is no actual PDP-11 involved in the 725/730/750.
And EXCHANGE has the ability to create "virtual" media images on disk.
The CONSCOPY script creates a virtual TU58 image file and then copies all
the files from the real console TU58 to the virtual copy. Why the copy has
an extra 512 bytes, I don't know.
I agree with Johnny - dump out the image and look for the RT11 directory.
Bob