Final Drive ratios for 4.5t

[B4 Sloth]

Have got a losi 4.5t brushless combo. It will be used in my yok bx, with a 6.5t in my ae B4. I know its fast but I will be using the facilities of the speedo to turn it down a tad!
Need to know what pinions and spurs to use, assuming the bx has a drive ratio of 2.2 to 1??

Thanks