I have too a Power Mac G4 Sawtooth 350 mhz, it´s a triple boot ( OS 9, OS X Tiger, OS X Server 1.2 (Rhapsody 5.6)) system.
80 GB drive size should´nt be a problem, my G4 has a 160 GB ide hd (computer sees it as a 128 GB drive). The drive is partioned to 4 partitions,
first is a 2,9 GB OS 9...
Well, i got both Performa 6400/200 and a Powermac 6500/250 with empty pram batteries for years. Both boot and run just fine. Maybe it´s something else..