PDP 11/04, like 11/03,11/05, 11/15, 11/20 lacks an MMU.    So the traditional releases from Research, USG, UCB will not boot.

That said, V1 which ran without it might work with some tweeking as they did not yet have one.  And if you could find a KS-11 MMU that Ken and Dennis had for the 11/20 (which was designed by DEC CSS), theoretically next versions could be made to run.   The problem is that while many of us have looked a: we can not find a KS-11 in real life (CSS did make that many), b: we can't even find documentation about it (Ken's surviving code is the best doc we have).

FYI:  go to bitsavers and download a copy of the PDP-11 Processor Handbook, but note the data.  You probably will want (at least) both an early and a later one, as the later ones often dropped details about some of the models that were not being manufactured.   For instance, I have a couple of different ones, and the '78 version really one talks about 04/34/45/55/60 - the previous processors like 03/15/40 are not included.  So you need an early 70's version to include them, and later versions for the 44/90 etc.

BTW:  Page 4 of same, have a graphic showing the HW requirements for the DEC OS's. On the X-axis is the OS, the Y axis the model.  RT-11, MUMPS-11, RSX-11M, RS-11S are the only OS's that were supported for the 04.

Here is a hint, if the processor could not support RSTS, it is unlikely it could support UNIX.