brushless opinions for Backslash 1/8 scale 2wd buggy

Hey guys, first of all I guess I'll say Hi since I am new here, So....... Hi.

second of all, I am building a backslash as seen here, http://www.ultimatetraxxas.com/projects/backslash/

I am going to run a mamba max on 3s and a vxl motor, Unless you guys think I need to go with a lower KV motor?
and if the VXL is fine could anyone reccomend where to start on gearing, i was thinking somewhere around 12-85 to 12-90 but that is just a shot in the dark from looking at soem other posts. all help is appreciated.

and Linc FYI buddy I have some more questions coming for you in the near future.