When you say you will be playing demanding games infrequently, do you still want them at full-tilt settings? I would just go with the 7970 GHz Edition. Honestly, the extra overhead is worth it, and it's going to make a difference at higher resolutions. To put it in perspective, one of my 7970s (pre-GHz Edition, they are OG reference models) has a hard time running Metro 2033 at 2560x1440 completely smoothly. I bring this up because the Oculus Rift is supposed to be displaying two images at 1080p in stereoscopy. That is a lot of pixels to push. Even bringing it down to 1280x720 each, that's still the same amount of pixels as a 2560x1440 display.

Heat, well...you did want AMD. It's not going to be Intel cold, but if the CPU couldn't take the temperatures it generates, it wouldn't be on shelves and have great reviews. Also, I wouldn't be against liquid cooling. That closed-loop unit the FX-9370 comes with is the same one I have on my i7, and it does a remarkable job. It's also the same unit used by Corsair and others, I believe. Your idle temps will be higher than on air, but your load temps will be way better than the stock HSF that comes with the FX-8350. It's also really, really quiet.