My First Mopar! Learn Me!!

Hello all!
I'm Billy and I grew up with Chevys mostly but I've always loved the early Mopars. My friend, the little brother of my best friend, Troy was given a 69 Dart from his brother who had gotten it from their Aunt. Before they cam upon it the car was sitting in her garage for 30 something years. Sadly and tragically Troy was murdered and the car sat for over a year before it was given to me. It is a beautiful car and holds a lot of sentimental value to me. It's forest green with a black vinyl top and black interior. It's the 4.5L V8 with 56,000 when i got it but now more like 84k.

I am slowly putting money into it but I'm not too familiar with mopars and what parts are interchangable and what kind of swaps people are doing. I just bought a 8.75 rear end to swap in but it came with 3.23 open gears. Does anyone have a lsd with 3.55 gears for me?

Also I'm eager and willing to learn more about these cars so any advice and input is gladly welcome. Until next time, Mo'par to ya'

where in ca?