Yeh I never did hunt out those wiring diagrams . What year is the engine from ? Pre or post 89 . Mk 2 GTI's the ignition was controled buy the computer , post 89 .
If its post 89 there are diagrams on
http://www.suzukiinfo.com/ . If its pre I will have to dig out the photo copy I have here somewhere .
I thought you mate was going to wire it up ?
Its not too hard to sort out . The best way to do it is cut all the tape off the loom , the black stuff so all the wires are exposed . You will need to reshape or shorten the loom anyway so you will have to rewind it . Then you will be able to start removing stuff . Basically tape the computer plug down and trace all its wires , when it goes to a dead end see what the conector is and trace back the other wires in the conector ( they will run to things like the fuel pump etc ) .
One thing to think about is the alt , the gti has a ribbed belt so you can't use a 413 one . If you use the gti one they are wired differently to a 413 one ( only two wires and they swap them , go figure ) , I would get a vitara one they are wired the same as a 413 and will be easier to find in the future .
I am a little busy at the moment and have no shed space to wire up a car but if you strip off all the black tape I could possibly strip down the loom to the wires needed to run the engine . You would have to post the loom up and tell me what the ecu number is so I can check I have one here as I would want to test the loom before I sent it back . Then you or a local sparky could wire it into the car .
I am away all April so do not have a lot of time , but it should only take a couple of nights to sort it out . Take a bit to remember it all

.
Either way let me know if its a mk1 or mk 2 engine and I will try and dig out the wiring diagram for it if its a mk1 . I will scan and e-mail it on monday .
Cheers
Chris