i've just done an engine conversion on a mk2 glof, going from a 1.3 carb to a 1.8 8v gti, not the same gap in years as you but still. with regds to the wiring. To do the wiring may be a simple task, (it wasnt for me i blew two ecu's, by having a bad earth connection.) if you can source the wiring looms, fuse box, and ecu, fuel pumps, then it shouldnt be a problem, take the loom out of doner car, it helps if its still attached to the engine, label every thing with address tags as you do it, and write on a seperate piece of paper the letter or number, (i found capital letters were easier as they couldnt be confused.) of everything you took off and what it connected to. note which grometts the looms came through, and swap directly to your car. Before plugging your ecu back in, wire up the batery and check there is a good earth at all points, the gearbox cylinder head etc etc. once checked, disconnect the +ive batery lead, connect your ecu and away you go. Hopefully. If you take your time, label and check everything throughly then things should be ok, and you can have the advantage of the bigger engine with fuel injection. Best of luck whichever way you go.