Due to my always tired during the work week but never tired once I'm off Air Force sleep cycle, I stumbled upon a website. I'm looking to go up one/down 2 and this site is pretty cool. Very simple to use. It has theoretical top speed, mph in different gear and stuff. Idk about you but this definitely solidified what I theorized myself. Maybe this can help you?
Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator
Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator