You will need intercooler and rad from a diesel 45 or ZS too. The electrics will be the hardest bit I would have thought because no loom is plug and play.
Regarding the brakes, the Ti discs wont fit the ZS because they have a different PCD. You can make the front Ti calipers fit with 282mm ZS 180 discs but you will have to open up the carriers slightly because Ti discs are 23mm wide as opposed to 180 discs which are 25mm wide.
The wheels wont fit either.
Seems a shame to break a nice condition 620 ti just for the engine as they are getting rare these days