Taller Tires Needed

The speed at a given rpm is directly proportional to tire height. A 10% increase in height means a 10% increase in speed at a given rpm, or a 10% decrease in rpm at a given speed. On the other hand, with your current specs you should be cruising 3400 at 70, not hitting 4k until around 83.

A 29” tire should put you just over 3k at 70.