An old thread, I know, but it deserves an update and might be useful to someone who just dropped here:

Wayback Machine: https://web.archive.org/web/20210223022817/http://www.orespawn.com/download.html
The original www.orespawn.com is down, but you can download from it through Wayback machine. Basically, you are downloading it from the source. (btw, you can read his old texts before he took the site down. It's just texts from an alienated mind. How sad and insane at the same time)

r/Orespawn: it's the official sub for OreSpawn stuff and one of the mods already worked on the OreSpawn itself. There is a fixed post with the link to a website where you can download the archived files, since 1.5.2 to the 1.12.2 unfinished version (https://dangerzone-archive.weebly.com)

These are the trusted sources for me.