Overpriced is more like it. How much was that puppy? I would only add an Alternator over 100 amps if I had a huge bank of amps and video equipment to run while idling at a show. You would know that you need it because the amp draw would be greater that the alternator charge showing a negative on an amp meter. As far as a 25-45 dollar 65 amp LIFETIME replacement alternator at Autozone, you can't beat that unless you have to have the bigger one.
At the local Junk yard over the weekend, I also noticed on the late '70s and up Mopars they used a larger than 10 guage ALT Charging wire. It looked more like an 8 Guage. I always changed it to a 10 but after seeing this, I'll start using bigger wire. I might have to double up on the fusible link too because the largest size I buy is 14 guage but I want to be able to handle at least 100 amps. I think 2 parallel 16s would probably do it.
Rob