The H70 would be better but so would the noctua u12p for alot less than the H70, you could also look at the nh-d14 if you have the money for the H70 as its cheaper than the H70 and it mullers the H70, U12P and N520 by a long shot, if your not planning on overclocking your cpu the u12p would work nicely to silence your set up and give you better temps than your current N520.
TL;DR dont get the h70 if your going to overclock get the nh-d14 if it fits, if your not going to overclock or are only going for a small overclock the u12p would be better than the h70 for noise level and temp reduction over your current cooler
NH-D14 (Just make sure it fits) > H70 or u12p (u12p if the hnd14 wont fit) > your current n520.