fergusontractors dot org has a wiring diagram section under resources.
To connect a 3 wire Delco alternator:
Large stud on alternator connects to ammeter (same wire that connected to BAT terminal on old regulator.
#2 pin on rim of alternator connects to large output stud.
#1 pin on rim of alternator can connect to output of your present switch (same wire that goes to the coil). Install a diode in this wire. You do not need a new switch
Use diode rated at 1.5 amp@ 50 volts or greater such as Radio Shack 276-1661 or similar. Band on diode goes toward alternator.
The L wire on your old regulator supplied power to the light and ignition switches. This wire can connect to big output stud on alternator, or you can swap this wire to other side of ignition switch and use it with the diode. If so, connect input to switches to alternator side of the ammeter.
It would be a good idea to replace alternator to ammeter to start solenoid/battery connection with a 10 gauge wire.
With 3 wire alternator you do not need to rev cold engine to get it to start charging, it will be less prone to run down battery if it sets for an extended time, and it will probably be much cheaper than a 1 wire.
Your alternator (unless specially modified) must be negative ground. To change from positive to negative ground connect battery with negative post to frame. Turn on switch but do not start engine, and if ammeter swings to positive side reverse connections on ammeter. With negative ground the negative post on the coil goes to distributor.