You will need more than just those two gears - the idler shaft atleast and probably even more, see the exploded views.
If I have the time (and interest) I'll try to see what exactly is needed or can it be done with minor modifications to existing parts.
New video available, click the pic below to see it on YouTube.
Had to change the esc to MGM ComPro 12018-3 because I got smokes from the LT-6S-150A...
Also upgraded to RPM a-arms and changed back to stock hex adapters, because the E-Maxx ones started to wear from center hole, which caused probs with wobbling tires and changing camber.