Since you have the 290, there is no HDMI 2.0 port on it, and since there are no monitors that's above 40 inches, TVs are your only option. The only 4k TV in the world that has DP 1.2 connection (Only DP 1.2 on the 290 will give you 4k@60Hz) is Panasonic.
Right now they only have the AX800 available in 58 inches and 65 inches. AX900 will be out...whenever. But the point is that only they have DP 1.2 on a 4k TV, so they are your only solution at the screen size that you want. It is one of the most high quality 4k TVs out there, so the response time/input lag is not too bad to the point you can't play anything, feels just like a normal monitor as long as it is a high quality TV and not a cheap one...