Is there any documentation on which boot blocks should be used on a
   particular type of machine ?
   
   I'm trying to replace the boot disk on a SS2 with a larger one. Both
   disks are currently connected to it, but I'm running off the old one
   to do the install.


you probably want to use the /usr/mdec/binstall script... it typically
is used like:

	/usr/mdec/binstall ffs /mnt

where /mnt is where the new disks root filesystem is located.