Belta half cut with 1.3 is a very good option. In fact I will say that it is better than 1.5
The reason why I say this is, that when you buy the half cut, you'll get everything.. the engine, transmission, mounts, axles, wiring, ecu, sensors, suspension etc which you can bolt on directly to your car without any alteration.
This will be as close to a factory fitted 1.3 as it can get, and later on you won't have any problems either.
1.3 will give you a very reasonable drive and pulling power and you will never feel that the engine is underpowered like you feel in 1KR
If you go for 1NZ, you will have to run around in collecting parts separately since you won't find a complete 1.5 nose cut for belta. And then it will involve modifications.
Lastly, believe me, 2NZ is less noisy than 1NZ. That is, 1.3 makes lesser noise than 1.5, which is inherently a loud engine.