range rover diesels

hello, got a question about the older range rovers 2.5 diesel (bmw engine). i've heard these are slow and i know you can get chip and bit and bobs but can you swap this engine for the bigger 3ltr diesel (also bmw engine) found in the new range rover the td6, or as its the same family of engines the bmw x5 3ltr d. would the td6 or other variation of that engine fit on the older gearbox etc....

many thank look forward to reply