i think ive done a pretty good job piecing the mk3/mk2 harnesses together.
basically what i did was remove everything from the mk3 harness that doesnt pertain to the engine.
then i'll use the mk2 harness for everything else (lights, a/c, fans, blinkers, hazards)
i repaired some of the cut off connectors at the engine with some connectors from the mk2's old gas engine harness.
repaired and re-spliced all the brake/clutch switches with a combo of mk2/3 stuff
the A/C wiring was pretty tricky, im using mk2 lines with an adapter at the compressor... im not sure if i got the a/c wiring right but wont know until i get both the engine running, and the system recharged.
should be dropping the harness into the car this weekend, if all goes well it will fire up and if my repairs are all correct and everything works i shouldnt need another harness. It would have just saved me about 2 weeks of wire shooting, repair, and countless hours on the multimeter/staring at schematics until my eyes were crossed.