Haha, I'm about to perform a similar swap. I'm going from my 318i's L4 M10 or whatever, to a 325ia L6 m20 engine. Gonna be hot and sexy.
Haha. Just takes a damn lot of work from me. I've got a donor car, so I'm swapping struts, rims, tires, rear main, tranny, engine, computer, rear disc brakes (included with strut...:P), Shit. what else. There is so much that will be going into this. The engine, tranny, rear main, and struts are first tho. (with the computer and wiring all that jazz being a given.) Ill try and swap the rest over slowly. Rear struts may not happen right away. Gotta figure out whats going to happen with alot of my cars systems. Gah, tis gonna be alot of work. >_<