Here are all the device IDs from the ATI7000Controller.kext with the model numbers:
0x22001002
0x26001002
0x67801002
0x67901002
0x67981002 HD 7970
0x679A1002 HD 7950
0x679E1002 HD 7800
0x68001002 HD 7970M
0x68061002
0x68081002
0x68181002 HD 7870
0x68201002
0x68211002
0x68251002 HD 7800M
0x68271002 HD 7800M
0x682D1002 HD 7700M
0x682F1002 HD 7700M
0x68391002
0x683B1002 HD 7700
0x683D1002 HD 7700
0x683F1002 HD 7750
As tonymac posted above that even with the proper device id it's still not perfect.