Ecu relocation engine swaps

Hi

first post here.

planning to do a engine swap in a old BMW 635, going to use the n54 engine out of a 335i e92.

On the e92 ecu is located next to the brake booster on left side of engine compartment.

in the 635csi the ecu is located under the glovebox (lhd vehicle).

the oem wiring from the engine is too short and stiff to reach the orginal location.

what would be my best option, making a new loom from scratch or subloom?

regards

geir