file-related Any compression masters here?

Hey all. Any video compression masters here? I have a 640x480 ripped VHS video that is 5 hours. It currently is 72 GB. I used handbrake to compress with h265 (RF20). Now its 8 GB and looks great. BUT I downloaded a Game of Thrones 5 hour video at 1080p thats only 4GB and it looks amazing. So I assume I can get way better file size compression than 8GB. Any ideas?