A "super-7" CPU like a K6-2 500 can usually be used in a vanilla socket-7 board. There are two potential issues: if the board doesn't support 100MHz bus speed then you can use a lower bus speed with a higher multiplier ie. 83MHz * 6x (the jumper setting for 2x results in a multiplier of 6x for K6-2/3 CPUs) The other matter is voltage: your CPU probably calls for 2.2 or 2.4V and the board might not go lower than 2.8V. In this case the CPU should be fine with good cooling at 2.8V, but the current draw of the CPU may be higher than what the board can handle (touch the heatsinks on voltage regulators near the CPU socket to check...)
Anyway I have a good collection of CPUs here if you still need one.
