There are several paths you can take, some are simple upgrades that work well for stock electrical systems, others are a bit more involved but can handle anything from a little bit more electrical load to dramatically more electrical load, especially at idle. It's best to put in a system that meets or exceeds your actual needs, while keeping in mind "the weakest link" concept.
Power output from all Mopar and many traditional replacement alternators such as some of the japanese types commonly used is notoriously poor at idle rpm.
The best option i've found for my electrical needs is a late model Delco-Remy CS144 alternator. It bolts right on with a simple bracket adaptor, puts out over 100 amps at idle out of the box, is heavy-duty, affordable and easy to source.
I'm adding several power hungry accesories to my 1970, A/C, two high amp electric fans, a powerful Performance Engineering fuel pump, aftermarket ignition and a few other goodies; and I wanted even more power at idle and low rpm, so I had the CS144 i'm using upgraded with a heavier duty voltage regulator & bridge rectifier and a rewound stator.
It's now capable of putting out over 115 amps at a slow idle and over 170 amps at moderate speeds, but only provides what's needed. It also has remote voltage sensing, so the trunk mounted battery gets full voltage to compensate for the voltage drop in the long run of cable to the trunk. Yes, it's a bit overkill, but so is the rest of the car.
I'm running a 2 gauge cable with a 200 amp fuse from the alternator to my main electrical distribution block under the hood. I'm still in the process of building/upgrading the rest of the electrical system in the car to handle the new electrical power needs and safely feed the original electrical loads such as instruments, lights etc.
I found that using marine grade electrical components and reading the information at Mad Electrical has helped a lot in my quest to use quality parts to upgrade and enhance the safety and performance of my old Mopar.
