I could not get arcos .8 running on PROXMOX at all. Multiple tries, ide or scss, danis or IBM drivers.
No ability to install the client!
Leave the SCSI, I have doubt it will work.
DId you test the SATA option ? Try the DANIS506.ADD driver ?
At least in a article I found on the internet they mention SATA.
If you try it where does do you end up ? Does the boot hang during boot from install media ?
Or do you not have any disc storage when the installer starts up ?