Here are my calcs for 3.9:1
@6500 RPM
1st 2.66:1 = 77KMh
2nd 1.78:1 = 115KMh
3rd 1.3:1 = 157KMh
4th 1:1 = 204KMh
5th 0.74:1 = 276KMh
6th 0.50:1 = 410KMh
Cruising @ 100KMh in 6th = approx 1600RPM
Calcs for 4.11:1 diff gears
1st 2.66:1 = 72KMh
2nd 1.78:1 = 109KMh
3rd 1.3:1 = 149KMh
4th 1:1 = 194KMh
5th 0.74:1 = 262KMh
6th 0.50:1 = 389KMh
Cruising @ 100KMh in 6th = approx 1700RPM
These numbers are based on my 315/35/17 rear rubber.
Cheers