I don't know any G8 guys running the West Coast Cylinder heads, but do know a CTS-V guy running them.
Rick Crawford in South Carolina is the guy to go to for head porting and throttle body porting. He also has an intake manifold modification that he does that yields some great gains. He goes by G8-4-speed on the g8board.com and grrrr8.net. The guy knows his stuff and has guys coming from all over the country to do work for them.
He can work over a set of factory heads to flow better than the CNC ported GM heads.
He has a naturally aspirated G8 running in the 10's.
Pontiac G8 Conquers 10-Second Quarter-Mile (Videos!) - GM High-Tech Performance
So, it really depends on your goals whether it be horsepower, quarter mile times or both. Rick has some cams that he recommends to folks depending on their goals. For example some want a mild cam so that they can get by with a stock torque converter while others want something more wild that requires a stall converter.
Me personally, in my 6.0 (L76) I'm running stock heads with dual valve springs for the cam, stock intake manifold, stock throttle body, Livernois Stage 1 L92 cam, stock stall, Kooks long tubes, high flow cats, Vararam intake, and tune and I'm putting 407 to the wheels. It's not crazy power, but I can run 12.7s in the heat of summer and as low as 12.2 - 12.4 in some nice cool fall temps. I've run a best of 12.26 so far and that's with the stock GT gears which are 2.92s. I'm pretty content with it as it sits, but if I wanted to go faster, I'd have Rick do the heads, throttle body, and intake manifold and would add a converter and it should easily run 11's.
In contrast, one of my G8 friends is supercharged, putting 606 to the wheels and running 10.7s so there are definitely a bunch of options depending on what you want and how much you want to spend. His is so tame that you could drive it across the country in comfort.