I have a YouTube channel where I upload music from the Australian metal scene either at the request of the artist or by gaining permissions. Many are from cassettes I purchased that don’t have an online presence.
It’s currently new and building. While it doesn’t have a huge audience right now, I personally promote each video to various places whenever I get the chance. Places like Reddit, Facebook groups, twitter and any time I see someone asking for certain types of albums in discussions.
If you want me to upload it email email@example.com. I only need the files, I can produce the video.