I'm getting just over 400Mh/s, using a 6970 purchased from NewEgg:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814131394

AMD Overdrive Settings
GPU Clock 940 MHz
Mem Clock 1425 MHz
Power control +7%
Fan 76%
Temp ~73C

poclbm flags -- -w64 -f0 -v

I've gotten it up to about 450Mh/s tweaking with clock speed and power settings, but it wasn't stable.