It was your quoted RPM at 70mph that looks way off, and back to front.
Your adjustments for final drive gearing is ambiguous (you know, they/them) which is why I asked if your talking underdrive high range gears, or overdrive high range gears.
Haven't checked all your calcs.
Point being for...
Are you talking underdrive or overdrive high range gears?
Underdrive gears increase your final drive ratio ( lower hearing), and increase RPM at a given speed.
You seem to be suggesting underdrive gears 4.56*1.1= 5.016 is lower geared. And would increase RPM.
4.56 diff gears with 10% transfer...