I haven't done it before but I've wrecked them, both 33 and 34 turbo. 33 turbo brakes are different to my knowledge to the 34, some bolt holes need to be modified I believe, though it is doable.
You'll need a RB25DET non-neo engine loom as it has been said it is different.
Personally if I were to do it, I'd take a 34 GTT and put it in a NA 34 or using 34 bits for 33 upgrade. I wouldn't go putting 33 parts into a 34. Just a personal thing though.