don't think the UZ would fit. Some friends of mine commented that it's a wide engine although short. Wide is never gonna fit in a 46 engine bay.
There are plenty of E46 with 1UZFE, domestically and internationally. However, the engine bay is fully occupied that makes modifications very troublesome. Russians like to fit this engine into their E46, locally wise, i went to this Lee's Garage in Shah Alam, they have done a couple of 1UZ swapped E46 in the past with great success.
For modifications, 1JZ will benefit more as more working room. For stock standard comfort, 1UZFE will be good enough. The later version of 1UZFE packs 320hp N/A. Some simple IHE, ignition and ECU should get another 30 hp easily.
Thanks,
Ken