Slot A Thunderbirds have problems with the KX133 chipset when they're running faster than 800mhz.
There is one revision of the K7V, that being the K7V-T that supports the Thunderbird at the higher speeds. I can't remember the exact modification, but the board did need to be altered to eliminate the problem so a standard K7V will not work.
Any AMD-750 chipset board will support the Slot A Thunderbirds. Which means if you had a K7M, you'd be in business.