basically you'll need to buy a new flying loom
once you have that its a matter of starting from scratch, working out where the ecu will be mounted and running the lengths of wires to their correct locations and then cut, crimp new terminals and plugs on and wrap it all up in quality conduit/sheathing.
try and avoid soldering anything... everything must be crimped, checked and then heatshrinked then wrapped
make sure loom is not tight in any spots, allow for engine flex, and keep it well away from heat.
you'll need an array of wiring equiptment, crimpers, cutters, strippers, heatshrink, conduit etc
or just pay decs to do it