Welcome, I guess no one has answered yet. You can buy SHV here:
https://store.steampowered.com/app/4..._the_Atlantic/
The Berbster has a page with tons of tutorials on how to modify (mod) SHV to be playable. Here's a link:
https://www.subsim.com/radioroom/sho...d.php?t=211804
That should at least get you started. You'll likely have lots more questions. Ask away. I hope you get more timely answers than mine!
Cheers, and enjoy!