Well - I tried the bcdedit commands and rebooted and attempted to install the PCR-800 again to no avail. It did the same thing as before. But thanks for the idea.
As for the Orca thing, I'm not sure that's going to get me any further down the line because I think the problem is as much in the installer as it is in the drivers themselves in this case. Since the device is "recognized" by Windows after the driver is installed (goes away and comes back in the device manager when unplugged and replugged and shows as PCR, not unknown device), and it doesn't simply work by using the inf file install option, there must be some Windows magic performed in that interim detection step that the exe installer does.
I'm certainly open to other ideas as to how to make this work. My 8.1 re-install is running fine on my SSD in the meantime, and I've spent the time to get everything fully installed and configured over there (which of course performs better because it's on an SSD and because it's a nice clean install), but I'd like to get it working on the "old" installation so that I could then upgrade the SSD partition to the Windows 10 "trial" to get to use it regularly.
Thanks again for the thoughts.