The main things you need are the engine and gearbox, ecu and loom, front subframe and engine mounts. I did the whole conversion for aprox £800 including buying everything. I can highly recommend FK suspension, I have the konigsport model and they are amazing (possibly a bit pricey for a road car though - mines for track) Also, you can't go wrong with the brembos from an Ibiza Cupra R - these fit easily to mk3 hubs.