Would the Intel Core i5-4430 3 GHz Processor bottleneck gtx 970?
I don't whether to bother going for the 750Ti or the GTX 970.
short answer almost never will it bottleneck your GPU it's a fine combo.
long answer, it'll onlt be bottlenecked on game/programs that's considered CPU intensive, i'll try to make an example.
on a cpu intensive game (let's say ARMA) you'll have big increase on fps if you upgrade/overclock(if able) your CPU, but on games that's balanced, you wont see alot of increase in fps to justify further upgrade.