The ecu multi plug has about 100 pins! That is part of the engine loom so will also need to be swapped over.
It really isn't that bad to swap over the entire loom, once I had the engine out i was able to remove the wiring loom easily within an hour. Didn't take much longer to get back in.
If you want it done properly and running correctly you need to swap over the entire loom.

Got mine MOT'd start of June then drove it over to Germany and did the nurburgring end of june, had a few minor teething issues to start with but now it's 100%