In order to go back to Mopar alternator, you would have to rehook up this old system to use the voltage regulator, which is intended for use with the single field 36 amp alternator. A change to the newer style regulator should be on your list if you are going to upgrade the alternators output any. The 36 amp alternator is minimal at best, especially if you are running an MSD ignition system. I see the MSD coil, but It looks like the stock style points distributor. If you have points still, the 36 amp system hooked up as stock will run the electrical requirements of your car.Is this pretty straight forward, as it seems the old alternator wiring is gonzo. I'd love to upgrade to the better regulator and alternator, as well as electronic ignition to rid myself of the points.
FF
Here is a wiring diagram. If you use this with a later model "square back" alternator and regulator you will be fine. You'll have the additional amps and better charging system than the solid state. Make sure you know the amp output of the alternator when you purchase it and also that your charging system wires can handle the load. I went with a 4 ga from the alt to the starter relay and my alt is a 75 amp. A little over kill but I like it that way. I have already did the upgrade using the same wiring diagram. I was already running a aftermarket ignition. good luck
http://www.mymopar.com/downloads/1973/73BarracudaA.JPG