Hi @SkyBreach !
I don’t play CDDA these days but I like to read the forums once in a while.
Just passing by the forums and I wanted to wish you good luck with your soundpack! I know that changing and replacing all sound effects is an ENORMOUS task.
I tried myself to make something like that some months ago, but never had the patience to finish it.
Anyway, feel free to look at my soundpack if you want some more music to add in your pack (CCSoundpack 0.5 - Cendar Cataclysm Soundpack Project), there is a SOUND CREDITS.txt file inside with all the credits for each song I used (open it with notepad++ for good formatting), they all are either Public Domain or CC-C0 or CC-BY and by your pack description, I think some songs can fit in your theme.
I also used some new sounds effects, feel free to use them if you want, there is 44 new sounds that also are Public Domain or CC-C0 or CC-BY. (You’ll also find the credits in the .txt)
Happy apocalypse !