Just in case anyone is on the edge of their seats waiting for an update.
I have a nice matched set of four Barracuda 7200.10 ST3160215A drives that I've run through SpinRite and it says they're all fine. According to the information it's giving me, they have the same number of sectors and bytes as the original drives. I have a StarTech drive duplicator that I'm going to use to make clones of the original drives and then I'll start testing different scenarios to see if I can get the RAID to start working again.