I use a 43 inch TV for 4k gaming due to having consoles as well (Gamecube, Wii U and Switch)
to me, 43 inch is the perfect size for 4k, anything more its more difficult to have everything seen within your eye vision
I showed my setup with the 4k TV awhile back
except now I don’t have that TV anymore, I use a Philips android TV (Philips 5604 series)
btw, Android TV is much better than a regular smart Tv imo
maybe you can put $350 on a bigger android TV if they give you the option, should you want to try android TVs?