the 1.1 is multiplied by the 3.545 which gives you your 3.9 to match your front dif. You should be entering 3.9 for your gear ratio.
The diameter of our tires is 25, so the radius is 12.5, the actual radius under the weight of the car maybe 12 at most.
so at 3k rpms... about 66 mph
http://wahiduddin.net/calc/calc_speed_rpm.htm
Let's say you were in FL where the speed limit on the Interstate is 70 and under 75 you get a warning and you are just a bad bad person so you drive 74ish mph regularly...you'd be crusing down the highway at about 3400 rpms.