With XPostFacto, just go for OS X 10.3 
The 427Mhz CPU is probably a 400Mhz part with the bus speed slightly increased. I recall the PTP machines can run at quite a high bus speed (55 - 60Mhz), so you might want to experiment with the G3 at lower multiplier and higher bus speed in future.
JB
The 427Mhz CPU is probably a 400Mhz part with the bus speed slightly increased. I recall the PTP machines can run at quite a high bus speed (55 - 60Mhz), so you might want to experiment with the G3 at lower multiplier and higher bus speed in future.JB