For this type of conversion it is not easy especially the wiring,to make everything works(gauges/aircon/abs etc),sometimes lot of things cant work,more over nowadays car runs on CAN/Multiplex system for almost everything inside the car.It depends on how the original system works.More over if fitting engine from different brands. And the more advance the donor car wiring system is,more headache to make everything run,some times we need to use 2 ecu,the donor car and the engine ecu.
Better have same wireman doing the work from A to Z,means he take out wiring,then mechanic take out engine,fit new engine,then wireman do wiring of the new engine.Even better if the wireman is the mechanic doing the transplant.