Well, the 320i is plenty of power if your only drifting for the craic! Obviously you won't win any competitions but it will get you around. The one i have has been very reliable despite three days in mondello close enough to the limit for two hours! The main thing with bmws is to get a good base car, once you have that the engines in the e36 bmws all use the same mounting point so you can go all the way to a m3 if you want more power, conversions are fairly cheap.

Heres a couple of pics of my 320i with welded diff,hydro handbrake, redstuff pads, 15" alloys and stripped out. All you need to get goin really