Revision A Apple II SCSI card problems

[cra@wpi.edu]

I have a ROM 01 GS with a TWGS running at 7Mhz and a Rev A Apple II
SCSI controller with a 412MB Seagate HD.  I am having trouble with 
ProDOS 8 locking up occasionally when it calls the device driver on the
ROM of the SCSI card.  It usually just pauses for about 3 minutes, and then
continues.  Other times I get an I/O error.  I also can't boot into GS/OS.  I get
an error code $27 when it tries to load GS.OS, but if I boot off a floppy with
the System 6.0.1 SCSI drivers on it, I don't have any problems reading or
writing to the hard drive.  I believe the problem is with the old Rev A ROM
on the SCSI card.  Does anyone know where I can get just a Rev C ROM chip
and not a whole new card?  It may also be possible for me to burn an 
EPROM if I can get an image of the Rev C ROM.  Any thoughts?