Connecting Atari 7800 Cartridge Port to Raspberry Pi 3

[Javamacc489]

I want to connect an Atari 7800 cartridge port to a Raspberry Pi 3 via GPIO so that the Raspberry Pi can read a cartridge's data and play the game through an emulator fronted by RetroPie. I already have original Atari joysticks connected via GPIO and are mapped to keys using the Adafruit RetroGame library. I'm using it with RetroPie and would like to further enhance the project. Before I start I would like to know, is it possible to do? I watched Ben Heck's Hand Soldered Portable Atari 2600 video on YouTube (https://www.youtube.com/watch?v=21qZKo0f280) and saw that he used an Atari 2600 cartridge port with custom controls and sound/display, so I know something close to what I want to do is possible.

If the project is possible, the next few things I need to know are, what type of cartridge connector does the Atari 7800 use? (I read somewhere that it is "24 pin female card edge connector (12 pins on a side) that is connected to power, ground, and the address and data buses of the big 3 chips," but need confirmation.) Where can I buy one of these connectors without having to hunt down old Atari parts or taking apart an original system? And, what do each of the connector's pins connect to, and how do I attach it to a Raspberry Pi 3? I'm thinking that I will need an additional piece of hardware such as a microcontroller to do this task due to already using many of the Raspberry Pi 3's GPIO for the joysticks and other buttons.

My knowledge level in electronics is mainly based on programming video games in Python or Java, but I know how to work on a Linux terminal and use an Arduino microcontroller. (I felt like a hacker when I added my own Python games to be played on RetroPie - however novice that is.) I hope you can help!