Savage X 4.6 brushless gearing question?

Hey guys.. I just finished getting all the parts together for my conversion. I'm taking a Savage X 4.6 w/ the XL 3 speed tranny and converting it over to electric power. I have two 2s 8000mah lipos and a castle mamba monster max with the 2200kv motor. I'm just wondering if anybody has any suggestions on gearing? Ideally I would like it to hit about 40mph, but not sure if that's safe to gear for that on only 4s. I was going to run 16/47 gearing, and will be doing mostly offroad bashing with the occasional speed runs. Anybody have any experience with this combo? Thanks a lot, really appreciate it!!