Here are my neoscrypt.cl and sgminer configurations for 7950 and 280x. I use the 14.6 driver, found no difference using 14.7.
My 7950 does 320KHs at GPU clock 1000 MHz, memclock 1250 MHz, 1.081V GPU core voltage
My 280X does 360KHs at GPU clock 1036 MHz, memclock 1500 MHz, 1.025V GPU core voltage