Early N54 engines were fairly overbuilt - a lot of forged internals.I like the looks of it, and have no doubt all the BMW parts are quality kit - their engines are very well tuned and have great driving manners. All that being said, 2 things:
-The engine won't be able to have massive modifications done to make huge reliable power like a 2JZ. Those days are done with pretty much any engine, especially an aluminum block BMW one.
-You need to understand that what you are buying is a BMW. And be prepared for the associated maintenance and parts cost that comes along with it. They are great cars, but like any german car they are over complicated, hard to work on and parts are expensive.
Boy did BMW correct that in a hurry