Using the cpufsb program in windows 98, you can overclock the IA-1 from its default speed of 266. Although there is no option to change the multiplier, you can select bus speeds of 60, 66, 70, 75, 80, 83 (most with fast and slow PCI speeds) and higher.
Naturally going from 266 to 280 or 300 isn't much of a difference, but for no work at all, I'll take a 10% improvement (see below). The 80MHz setting also seemed to work, but I didn't try it for longer than a minute or two. It seems to be very stable at 75 and below.
80 seems to be okay, but 83.3 crashes it. It seems that changed from a high to low PCI setting or vice versa, it will hang.
From sandra sisoft:
60MHz -- PR240; 446 mips
66MHz -- PR268; 508 mips
70MHz -- PR280; 536 mips
75MHz -- PR300; 556 mips pci at 37.5
75MHz -- PR300; 520 mips pci at 25
80MHz -- PR320; 595 mips pci at 40