Seems to me guys are too worried about torque. I suppose if you are running a 2 speed torque is more important that if you are using a 3 speed. If you have 4 or 5 gears, total torque and the shape of the curve are less important than if you have 2 or 3 gears.

If I know that my minimum engine speed is ( for example) is 4500 rpm (stall speed or on the chip) I can see no reason to care about torque (or horsepower) at a lower speed (say 3000 rpm).

All that said, your numbers posted are a fairly loose rule of thumb.