Thank youNoctua generally makes good fans but also keep in mind fans specs are the biggest lie in this hobby. I can't speak to how strong those fans are specifically but I'm sure someone else will chime in.
D5 pumps are large and I'm not sure they are a good fit with rads that are more restrictive. I would have gone with a DDC personally especially given the space constraints.
Run a 1kw load on a single 360 GTX? There are things that can be done just to be done, but that doesn't make it a smart idea. You'd need some serious freaking fans that would make your ears bleed to make the cooling acceptable. Back in the day ppl would run 600w loads on a GTX 120 for shits and giggles, yes it cooled it somewhat but it's a thing you can do not a thing you'd want to do. Two skinny rads even if HWL GTS will probably not be enough if you want good cooling with low noise and it's even harder with small cases.
D5 PUMP - I went back and forth on the DDC or D5. For me the space already existed based on the way the case modder desired the internal. And my research with DDC pumps are a little more noise, and run a little hotter. So that is why I went with the D5.
@Noci - Thank you so much! I can rock with the single D5. I believe it will work just fine.