The 8320 is going to run just as hot as the 8370 at 4.3GHz, if not less considering you won't be using stock voltage stepping if you do the OC right.
Plus, the heat output at 4.3GHz on Vishera won't be too bad. Maybe 70w idle, 170W loaded with both processors.
Just trying to save you some money man. 8320's are binned very well.
It's Asus C6H, not CH6; Fighting the wars that matter.