[Estoril Blue 116d]

This question has been lurking in the back of my mind for the last couple of weeks. Can it be done and what engine will fit? I'm talking about a relative plug n pray solution without big modifications and crazy fabrication. OE as long as it's possible. Swap as much as possible from a donor car.
Roughly engine, engine-mounts, radiator, plumbing, exhaust, gearbox (necessary?), driveshaft, diff and ECU...

To get it approved by the authorities in Norway the power output can't be more than the most powerful 1-series, say the M135i. It doesnt't matter if the power comes from a gasoline based model. The car already have the brakes and suspension to cope, and that's really what they are looking for when approving.
The goal would be around 300 hp. I will remap it later, after approval.

Reason 1: I've been planning to swap another engine in my E30 for a while but never got around to get it done. I think I might be better off keeping the car with it's original engine and sell it next spring. That money will be invested in a new classic car project, but some could also go in the F20. I alway wanted to do an engine swap and I really like the 1-series...

Reason 2: It would be one slick ride. A sleeper with a lot of diesel grunt. It would go like a freight train on steroids, smoking tires in third on dry roads.
I need the practicality of the 5 doors, and I already have the car.

So what do think, can it be done? Has it been done? Which engine will fit?