Fair enough. I don't live too far away from Newport now, and there are several state roads in the area I hadn't traveled yet, and I had a day off, so I took a drive down there and
took several pictures. Apologies for the quality in some of them; a combination of low sun angles and a dirty windshield is not very forgiving.
I don't know what happened between 2016 and 2018, but as of late 2020 US 321 is clearly signed along 25/70 through town, turning at McMahan. Although SB 321 trucks are instructed to turn at Main Street and follow the train tracks, other than TO I-40 trailblazers, no other signage is posted along that route in either direction.