Ok, good news and bad news!
The good first: I had the file! so I uploaded it here: Pitfall 3
Bad news: the game does not run on the Atari 2600. It was not meant to be a continuation. It was not made using a programming language either, but rather a drag and drop visual game building program. But I might at least bring the visuals very close to the Atari 2600 (using its color palette and perhaps respecting the scanline coloring. But I won't recreate flickering, lol