Not sure on the rpm I will have to review the video on a larger screen to hopefully read the tach. There is a set of 28 12 MT ET streets for sale (bias) I am looking at
Going from 31-28 inch tire,
Calculator says about 5000rpm at 107 mph with your gear and 31 inch tire, about 5500 with 28 inch tire. Converter slip isn't taken into account though.