Um...
Why are we talking about Thunderbolt cables?
You said you overclocked to 75Hz so whatever you use already apparently works fine. Plus, the monitor supports only DP at 4K I believe.
I know there's DP compatibility with Thunderbolt cable, but again if you already overclocked the monitor (presumably with a DP cable) why are we discussing Thunderbolt?
Are you going to add an APPLE computer? If so, does it actually support 4K at 75Hz as an output option?
OTHER:
I'm not sure but Thunderbolt v1.2 (both GPU and cable must support) supports DP v1.2. So investigate what is supported by that, though if you have a DP 1.2 cable working (not 1.2a and not 1.3) then I guess it's possible.