its not that big a challenge, though finding bits that work can be. the simplest way is to just pick up a tc3 motor mount and a ntc3 single speed input shaft. your on your own for holding the battery in though. i did this conversion but didnt want to spend money. if your a little mechanically inclined you could make a motor mount/battery holdin quite easily out of cheaply available plastics.
I put a middle dif in mine for rally use. wouldn't expect an ntc3 to handle particularly well as an electric onroad racer. if you just wanna mess with it on the street, it handles ok, but wont keep up to even a $100 racing kit.