O/S Reloaded, /backup Data Intact
After some hiccups with the datacenter—which I’ll be addressing with them this morning—the operating system is installed on the new primary hard drive and cPanel/WHM is configured. I’m configuring WHM before heading to the office, and I’ve had /backup remounted to the machine, and all the data appears to be intact. I’m very happy about that, obviously. 
Given the hiccups with the datacenter, I’m not sure how quickly I’ll be able to bring the server online, because I don’t have access to the ports for WHM from work. [I'm firewalled.] Also, today’s a busy day on my calendar, so I won’t have a lot of time to issue commands with one eye from time to time. I don’t expect much, if anything, to be back up and running today, given how things have shaken out.
Thank you for your continued patience.