I think that if he's friend doesn't mind on having a 200$$$$ case, you can put a E6700 in there.
All the rest is very, very good.
I choose the QX6700, just for the bragging rights......Joking.
And that E6700 should get to 3.5/4 ghz on water, so it will no be much of a bottleneck to the gpu.
Some testing here indicates that single card setups stop scaling at relatively low CPU speeds, so the E6700's headroom isn't really necessary unless you want to focus on CPU clocking. As far as bottlenecking a G80 is concerned, the E6600 seems sufficient.