In most cases you should not try to install system software directly onto a PowerBook in SCSI disk mode. The system software installer checks the type of computer that it is run on and installs the appropriate software for that computer. So, for example, if you connect a PowerBook 1400 to a PowerMac 7500 using SCSI disk mode and then install system software directly onto the PowerBook, you will not get any PowerBook specific software such as the PowerBook control panel. The installer may install incompatible software even when going from PowerBook to PowerBook if the two PowerBooks are different models or speeds.
The recommended way to install system software via SCSI disk mode is to drag the entire system software install folder onto the hard drive of the PowerBook. Then, disconnect the PowerBook from SCSI disk mode, start it up from a Disk Tools disk, and run the installer from the hard drive. If there is currently a bootable System Folder on the hard drive of the PowerBook, you can start up from the hard drive instead of a Disk Tools disk.