Hi Len
What are the jumpers on the drive? There should be about 6 of them.
I've never owned a GVP HC+8, but, I think it is a SCSI interface/ram expansion Zorro II card (meant for the A2000). The ram is probably 16 bit, not 32 bit. The SCSI interface should also work in an A4000 (so will the ram, but it will be slower). It seems that Jumper 4 enables Autobooting. I think jumpers 10 thru 12 set SCSI ID of the controller itself. If this is true, the drive and the controller can not have the same address.
There are SCSI diagnostic utilities on Aminet. I'm not with my Amiga now, but try to find one that will "poll" the SCSI.device. Get one that will allow you to change the device to GVPSCSI.device.