Not sure why you enabled gamma processing, or why you modified the HDR settings away from "let madVR decide". If you did these changes for a reason then it's fine, otherwise I would revert those to the default settings. Also, please make sure you have the "HDR and Advanced Color" option in the OS display configuration *unchecked*. That option is seriously bad.
Not sure what you mean with the black bar stuff? Are you talking about scaling 1080p movies up to 4K, so you don't get black bars around the video image? That's definitely what you should do. But upscaling to 4K costs a lot of GPU power. If your GPU can't handle the stress, then I'd suggest that you use a cheaper chroma upscaling algorithm, because that's not really all that important for image quality. E.g. try Bicubic75 with Anti-Ringing enabled, instead of NGU, for chroma upscaling. For image upscaling using one of the NGU variants is definitely a good idea, if your GPU can handle it. For image downscaling I would recommend SSIM1D instead of DXVA.