I tried this too, it is not as smooth as it looks on the OP.
lxdm for one thing seems to be of an archcraft configuration requiring lxdm-gtk3 (together with their theme-ing) while lxdm service needs to replace it. You can adjust the service.
Plymouth, other than being removed it needs /etc/mkinitcpio.conf edit and remove the splash hook to it.
networkmanager if replaced by dhcpcd/dhclient needs some cleaning as well. Tear everything that comes up relating to this monster away.
/etc/os-release moved to /etc/os-release.archcraft or deleted, before base can be installed.
When you think you are done, make sure filesystem is from obarun ... somehow it slipped through the pacopts for me.
That mpd/mpc music player they have can't work on Obarun unless rebuild without the dependencies to the nastiness.IBM
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Easier route, much easier, and much much cleaner!
Add
# # Archcraft Repository
[archcraft]
SigLevel = Optional TrustAll
Server = https://archcraft-os.github.io/archcraft-pkgs/$arch
to the bottom of your obarun installation's pacman.conf, no keyring to add. Use their fonts and themes from the repository to your openbox or bspwm setup to get the archcraft flare and touch. Actually, among the various openbox spins I've seen this is the one with the most work done on it, if not the best. Between systemd and all the stuff running on those WMs it is about as RAM/CPU heavy as an obarun full desktop, but that is besides the point.
You can copy /home/liveuser/* into your home if you think you can't do it on your own, but I wouldn't trust all the choices in /etc/
Their installer is just like Calamares without the gui, it just copies the live system into a partition, then changes liveuser to your username and PWs, hostname, kbd, locale.... but at least he is doing it right unlike many other "popular" distros.