Don't be so fucking stupid! They wouldn't know how to wire up a plug

Only wiring that lot know is how to hotwire a car to nick it

Just get your main 3 wires sorted.

Switched live (black)
Thick red -blue trace fuel pump relay
Live (thick red)

Depending on which car the loom came from, could mean totally differn't wire locations. Off the top of my head, heres a pointer

GTE loom:

fuel relay is in the engine bay, or you can splice into the same wire at the loom plug, although i would advise against this as its dodgy to get the right one.

Switched live can be spliced in just where the engine loom comes out the right side of the engine, as can the live.

GSi (cav, calibra, Astra) looms:

Fuel relay is in the driver footwell under the ECU. Just do the wire crossover there.

Not sure where the switched live is on these looms. sorry