Yeah, that's the deal.

Tire revs/mile times axle ratio equals revs at 60 MPH in direct drive. Revs at any other speed can be ascertained by linear proportioning, plus add a fudge factor if the car has an auto trans with a non-locking torque converter.

In the case of my five speed, since fifth is indirect, I have to multiply by the gear ratio:

(849 x 3.27)0.80 = 2221 revs at 60 or (2221) 7/6 = 2591 revs at 70

Duke