Athlon X4 750K is AMD A10-5800K without iGPU, so Athlon X4 760K should be AMD A10-6800K, I would suggest go for 760K if its possible, as there are few tweaks and it overclocks better. Get a good A85X and OC crap out of your 760k/750k, but dont forget about cooling.
And get a good GPU, 7950 if getting cheaper and GTX 760 is a good alternative. Dont worry about bottlenecks or expensive ram, Athlon dont need hi speed memory.