I did a bios dump to get a copy of my bios, since I could never find an updated bios for it. Included is a copy of the HTML file from AMD's website that listed some of the jumper settings. I actually run a AMD K6-2/500mhz on it, without any problems. You just have to fiddle with the jumper settings. A clue is that the jumper settings for FSB and multiplier are identical on many AMD K6-2 capable boards, as they simply reflected the necessary pins being shorted on the CPU socket itself.
If you are careful and extrapolate, then all is well.
In the BIOS, anything above 400mhz won't be reported properly, but Windows will show it at the correct speed which is not uncommon when dealing with outdated bioses.