Well, I figured out what was causing "cannot open gvpscsi.device unit 3" - something called "EMERGENCY_CD" was in the DosDrivers folder. I accidentally clicked on it and it gave me that error, so I removed it (just moved it out of the folder), and I no longer get that error on boot.
Now, I downloaded and reinstalled the GVP SCSI software which seemed to be mostly missing from the system before.
You know, I have nothing attached to unit 3, should I just set it to unit 3 and see what happens?
Also, bizarreness: There is something called KingCON-mountlist in DEVS:DosDrivers/ but no "mountlist". I cannot find KingCON anywhere else on the system.
This thing seems messed up. I would have just wiped it out and loaded 3.9 fresh, but alas, I couldn't get the CD drive to work :p