You`ll need a 9500 nonpro with the 9700 pcb layout, which means that the ram chips are placed in a "L" formation (two on one side of the fan and two on the other)
Also the make of the ram are important, the Samsung2.6ns are the best, you can get a fullt o/c able 9700pro !! The "worst" is the Infineon3.3 which is hardly able to pass 300mhz ddr
The original clockspeeds of a 9700pro is 325/620 (310ddr)
If you hardmod it you can flash it with a 9700pro bios and you`ll never need to worry about patches etc in the future.
I was only able to get a Sapphire with Infineon3.3, so I`m on a 9700np softmod....works like a charm, but the 9700pro speeds are probably out of my range...maybe with ramsinks and a heatpipe...dunno
You wont find one i a store so your best chance is to get a second hand one...