here is a chart that might help you out. i guest on tire height at 25"
sorry i made a mess of this but you can go on there sight and do some figuring on you one
Engine Speed (RPM) MPH 3.91 Gear MPH 3.23 Gear MPH 2.76 Gear
3500 RPM 66.58 MPH 3.91
3000 RPM 69.08 MPH 3.23
2500 RPM RPM/MPH From Gear Ratio Calculator by Wallace Racing
67.38 2.76
Here is the sight if you want to play around with gear ratio and tire size.
RPM/MPH From Gear Ratio Calculator by Wallace Racing