Bite the Purple Bullet
Bite the Purple Bullet and buy yourself a bigger PowerBook drive. Along with the cases that various hard drive vendors sell, you can now buy a $99 NuBus card from ETC Peripherals that will accept your 2.5" hard drive (or a 3.5" low-power drive if you buy an optional Purple Bullet Expander). The Purple Bullet provides a selectable SCSI address switch, an LED activity light, ETC Disk Tools 4.0, and all the necessary cables.
ETC — 800/876-4ETC — 813/884-2863 — 813/888-9535 (fax)