here's the working config file for my 3x 7950 machine.
"intensity" : "15,18,18",
"vectors" : "1,1,1",
"worksize" : "512,512,512",
"kernel" : "scrypt-jane,scrypt-jane,scrypt-jane",
"sj-nfmin" : "4",
"sj-nfmax" : "30",
"sj-time" : "1388361600",
"lookup-gap" : "0,0,0",
"thread-concurrency" : "35840,35840,35840",
"shaders" : "0,0,0",
"gpu-engine" : "850-1000,850-1000,850-1000",
"gpu-fan" : "25-80,25-80,25-80",
"gpu-memclock" : "1250,1250,1250",
"gpu-memdiff" : "0,0,0",
"gpu-powertune" : "20,20,20",
"gpu-vddc" : "1.031,1.031,1.031",
"temp-cutoff" : "90,90,90",
"temp-overheat" : "80,80,80",
"temp-target" : "70,70,70",
"api-mcast-port" : "4028",
"api-port" : "4028",
"api-listen" : true,
"api-allow" : "w:127.0.0.1",
"auto-fan" : true,
"expiry" : "10",
"gpu-dyninterval" : "7",
"gpu-platform" : "0",
"gpu-threads" : "1",
"log" : "5",
"no-pool-disable" : true,
"queue" : "0",
"scan-time" : "1",
"no-submit-stale" : true,
"scrypt" : true,
"scrypt-jane" : true,
"temp-hysteresis" : "3",
"shares" : "0",
"kernel-path" : "/usr/local/bin"
I'm pulling 334kh with a WU of 340. My system is stable and vddc for each card is holding at 1.031, core clock at 1000 and memory clock at 1250.
..i think this can pull @ 150 most, ill try to tweak it more. 
