You can use the Wallace Racing Calculators to work out revs for any given speed if you know rear end ratio and tire diameter.
http://www.wallaceracing.com/Calculators.htm
On the sand at Pendine the '29 CCPU in my avatar did 69.87mph at 2411 revs on 21" tires with a 3.27 rear end
Fun with maths. Who knew?