Locking the revo in 2nd gear to use motor braking/reverse

[z1nonly]

So after this mod is done, what would be the spur/pinion combo that would make it equivalent to 72/12 on an E-Maxx transmission. That is assuming that the Revo trans is equipped with a close ratio.

Reason I'm asking is because I might end up using a Revo trans instead of an E-Maxx trans for my E-Revo project, and I'll be running the Novak HV6.5 setup.