I just mounted a set yesterday. The rear is a taller tire. When the speedo says 77 its actually 80 by my GPS app thing. Bike didn't pitch me off because of the bias tires. Been running bias tires on radial equipped bikes for decades. I can't tell the bike knows the difference.
The rear tire mounted right up and aired up perfect. Was a little concerned about the more narrow rear versus the 6" rim width. No worries, works great. I do mount and balance my own tires.