Those would fit NICELY in my board (a 133MHz RS6/k PReP workstation with a PGA upgrade socket). But are you sure you don't want a flat pack IC for upgrading/repairing an accelerator?
Also, these are only 166MHz chips, not extremely fast...
But I have two machines and only enough memory for one, so I guess I could buy one of these and see if it works. If I break something I have more disk/memory in the other machine, no problem ;-)