I have a question about higher bitrate 1080p movies.

I have just gotten myself a 4k tv and while my media center isn't capable to playing 4k, I'd like to take advantage of the 4k upscaling ability. Would getting higher bitrate 1080p files help? I currently have the 1080p movie downloader set to look for movies between 1 gig and 7 gigs. is there a better way to set it up to get high quality items? I don't want huge files, but just want to take full advantage of up scaling capability.

Thanks.