What is the best display settings to use on my (unsupported) 4K 50" video display monitor connected to my MacPro?

I have a very nice 50" Samsung 4K display which I have connected to my brand-new Mac Pro, but unfortunately it is not supported by Apple (currently there are only five 4K monitors supported by Apple, and the one they recommend is the Sharp PNK-321). When I first got both the computer and the video monitor out of their boxes and hooked them up using the HDMI cable I bought at the Apple store, the image and graphical interface was so bad they were virtually incompatible pieces of electronics. However, a very helpful gentleman at BestBuy said that it was probably the cable, so I purchased a higher end HDMI cable (Cinnamon by audioquest), and now I have a fairly decent image and graphical interface. The trouble is, it is not nearly as perfect as the image quality and interface I have with my older iMac and all of my other Apple products, for that matter, including my MacBook Air, iPad, and iPhone 6+. The desktop background pictures look stellar, but the text is slightly distorted and fuzzy. I can live with it, but it's not ideal. Also, the electronic image I'm seeing on my monitor doesn't exactly fit the actual physical dimensions of my 50" display. The File Menu in the top left of the screen is partially cut off on the left, and the date and other stuff in the top right of the screen is partially cut off on the right. When I go into System Preferences-->Display, I don't have many options. I have to choose between "Best for display" and "Scaled". The Best for simply option makes all the icons and windows and text extremely tiny in size and is thus unacceptable. The Scaled allows me different sizes for the texts and windows, and so this is what I am using (scaled with the size option which is 2nd to the right on the "larger text---smaller text scale). I hope there is a way to fix/optimize my display settings otherwise I'm either going to have to learn to live with it or just cave in and buy one of the supported 4K video monitors. The problem with the latter are four of them are 32" and the other one is 62". They don't have anything inbetween. So what I would probably do is buy two of the 32" displays. They're not cheap. The Sharp PNK-321 is $2500. I bought my 50" Samsung for $1500! Thanks to all who can help with their advice!