Looking for an overclockable monitor also good for artists

[Kulagin]

I was given these requirements: 27", 1440p preferred, good for artists: monitors that display the colors very well, with good grades on sRGB, Adobe RGB and NTSC.

This one is good enough: https://www.amazon.com/Gigabyte-Monitor ... ss_tl&th=1

But we will also watch 3D Movies, so it has to be 120 Hz+. And then we will be playing fast-paced video games, too. So the bigger refresh rate, the better. And then when I told my friend that there are overclockable ones, so we decided to ask on the forum, which one would be the best to buy and then overclock the refresh rate as much as possible? Budget is under $300. The production year and new or used doesn't matter, my friend is willing to buy used to get the best product possible in the budget.