According this you should be able to run MK at it’s native fps/Hz of 54, so your TV should be scanning at 108 Hz.
Regarding higher than 60 FPS games, I can’t recall any game, but there are some, you should try those too. From AMD Freesync page
Low framerate compensation (LFC), allows AMD FreeSync technology to work when the framerate falls below the minimum refresh rate of the display. When the framerate drops below the minimum refresh rate of the display, frames are duplicated and displayed multiple times so that they can sync to a refresh rate that is within the displays refresh rate range. For example, a display with a 60 – 144Hz refresh rate, would be able to sync the frames of a game running at 40 FPS, by doubling them so that the display could sync and run at 80 Hz. A display with LFC effectively results in the removal of the minimum refresh rate boundary. All displays in the AMD FreeSync Premium and FreeSync Premium Pro tier are certified to meet mandatory LFC requirements.
My point is, with Retroarch and a VRR setup, you just “kill” the only reason real CRT were still needed: Native game refresh rate.