Technically no because the 8320 can be easily overclocked to 8350 speeds. And no, the 760 will not bottleneck either of those CPU because it doesn't work like that. The CPU is not dependent on the GPU. The GPU is dependent on the CPU. If you have a weaker CPU, there is a possibility of the CPU not supporting the GPU. If you have a weak GPU, you just have a weak GPU that's not going to perform at the desired level.
As always, make sure you have a good 990 board (or a very good 970, typically not recommended) to support either of those CPUs.