I've done a lot of motor switches. This was my first with a Porsche, however. I always try to make my engine transplants look like the car came that way from the factory (as much as possible). This forum has been a huge help in that regard in all areas including wiring. All the wiring changes below are prior posts by others on the forum.
Here is my standard 3 wire GM/Delco alternator...
The wire indicated by the yellow arrow goes directly to the + terminal of the battery.
The wire indicated by the green arrow loops back to the same terminal as the yellow arrow wire. This is the sensor wire to tell the regulator how much to charge depending on the battery condition and load.
The wire indicated by the white arrow turns the "idiot light" on and off and goes to the relay panel in the engine compartment.
Here's my relay panel...
The white star is the power relay. The yellow star is the fuel pump relay. Both of these need to be in place.
The wire indicated by the white arrow goes to ground. This wire "fools" the system into thinking there is a stock ECU in place and allows you to hook up a low pressure fuel pump for the carb in the same spot and with the same wires as the stock high pressure fuel pump.
The wire indicated by the orange arrow is the wire indicated by the white arrow from the alternator. It is the one that turns the idiot light on and off. It hooks to the terminal shown that the voltage regulator used to plug into (now no longer needed since the alternator is internally regulated).
The wire indicated by the yellow arrow is attached to a switched, non fused, 12V terminal on the relay panel. I am running my electric choke from this terminal.
Other than power to my fans on the radiator in the frunk, I believe these are the only wiring changes I had to make in order to install the V8. (well, there is the rev limiter and the TachAdapt, but those are easy ones)