Rebuild devices under /dev (I'm not sure if this is necessary, but 
   others recommend doing it):
   
   rm -rf /mnt/dev/[a-z]*
   cp /mnt2/sparc/tools/MAKEDEV.sparc64 /mnt/dev/MAKEDEV
   cd /mnt/dev
   ./MAKEDEV all

this _shouldn't_ be necessary....ideally they should create the same
devices with a few exceptions..
   
   The system seems to boot OK, even though owfboot in root filesystem is a 
   64-bit file

yeah.  ofwboot can load 32 or 64 bit kernels, regardless of what
binary format it is itself...