The "ATT UNIX v4.30.7z" is the original archive of AT&T UNIX System V Release
4.0 Version 3.0 I found on eMule. It comes as a set of 5,25"" floppies.
Unfortunately while the first floppy boot, other "fnd set" floppies fail to be
detected by the installer, because the first 2048 padding "0xF6" bytes are 
missing from the floppy images. Also, the second floppy of BSD compatibility
is slightly corrupted (1 wrong byte in the "df" command causing the program
to crash).

So, I made the "AT&T UNIX Release 4.0 Version 3.0.7z" archive, where I sorted
floppies by sets, and fixed alignment and corruption so all sets I tested can
be installed without errors. The floppy set seem to be the most complete AT&T
stuff, even though OpenLook floppies are missing from the set.

I succeeded to install the system on 86Box with networking, by using the
"i386DX/i486" machine type (don't forget to configure hard drive in the BIOS),
and WD8003E network card.

Installation on Qemu works fine too, with an IDE disk less than 500 Mo and
floppy controller. Unfortunately, Qemu doesn't emulate any supported network
cards for this system, and SLIP doesn't seem to be supported "out of the box"
even though https://github.com/mamccollum/svr4-386-slip/ might work (untested
though). Writing your own device driver for PCNet-Fast III or NE2000 could be
a solution though :o)