ok
1. that sucks you need a new engine
i know how that feels but i rebuilt mine instead.. at least i knew the full history of it and could in future rely on it... altho if you buy a jdm engine i suggest you do the mhg and arp head studs on it anyway at least you're not gonna blow a head gasket
2. dude..... theres no 3 litre twin turbo lol... there's only 3 single turbs or 2lt twin turbs... which depending on where you are you don't get
so i'm assuming you need a 3lt single turbo which is the 7MGTE
do a search on google or ur fav search engine for 7mgte engine or wreckers or suppliers or something and i'm sure you'll find something in your area where you could organise to get one
good luck with it and if ya ever need help with it feel free to ask