Rc8

Hi all!
I just ordered my RC8 conversion stuff. I a pretty excited here is what I got so far.
Neu 1512 2D/F
RC-Monster Mount
RC-Monster Battery Tray
RC-Monster motor end cover.

I am waiting on a 4s 5000mah polyquest battery and a Hyperion DUO charger and CC BEC.

I am also trying to decide if I should just order the MM or wait a couple more weeks for the MMM???

What gearing should I be looking at with this setup I would like to keep the top speed down to around 45-48mph .
Do you think I need to dremel the fins slightly to give me a larger range of gearing options??
Thanks!