MM + 9L on 12cells in med. weight maxx

[I Trust Tyler]

I originally had a 9920/7xl with 16-18cells in my maxx, but for some unknown reason the esc stopped working..whatev's im done being pissed about it. I have a couple of MM esc's not doing anything currently and i have been fiending to run my maxx. I just ordered a 9L and wanna run it on 12 cells just to use my maxx, this should suffice as long as i have the proper gearing and convert back to stock size wheels/tires right? thanks ppls.