I'm also going through the same nostalgia period. I have been researching everything I can find about Action! language, getting the software, cartridges, etc and determined to convert some old BASIC programs as well work on some new projects.
When the mood strikes, I like to boot all my vintage 8bit computers and have them run cool, but useful programs (like calculating lottery statistics or my own encryption techniques).
I has taken quite a bit of time, but I have figured out how to use my SIO2SD card (full of Atari programs) and then make floppy disks from them so I can write some code just like the old days.
So I too have been looking for source code examples (everywhere - also try Archive.org) and will be happy to share whatever I find or develop myself. Hope you will do the same.