There is a fair bit of info on my site for mx83 conversion(link at bottom of this post) .MX73 is very similar except for custom mounting intercooler radiator etc. A few guys like luke may be able to offer more experienced detail on this
your auto WILL NOT do use the matching auto for the engine you WILL need a half cut for crossmeber etc
But GET AN AUTO you only ever buy a 1jz manual for fun factor the auto is MUCH QUICKER