Motorola processors do not respond well to consumer level hacking. In fact, one of the easiest ways of killing a Mac is playing around with its clock speed.
If you want a dramatic speed improvement now, dredge the Internet in all the usual spots for Mac parts vendors (dont forget eBay) for G3 upgrade cards. G3 upgrades are highly available and with the MB buss speed on that machine will be about the maximum real performance increase that you will see on any computer of that era.
You do have one of the better pre G3 platforms to build a G3 off from.