Oops, I misspoke, the old system is Debian 5, lenny. The system the disks are on is running Debian 7, wheezy. And the system I am targetting is Debian 8, jessie.
So the chroot would be lenny while the real system wouldl be wheezy. The wheezy system already hosts VM's with libvirt. But getting things working as a VM seems a bit tricky. I can't simply hand the disks over to the VM because the host is using them too. And I'm concerned that anything I give to the VM will end up with vm control info written to it, at least if I'm not careful. Ross