There is a very good picture of what the factory harness looks like here:
914 harness site
There are only 4 wires:
One heavy red wire from the alternator to the starer. Red,brown,green wires that go from alternator to voltage regulator.
Its very simple, you might beable to build one w/ components from your local Ace Hardware. Or you could just buy one for $35.00 at site listed above.