I'm not 100% following, but if this is content that's gone from being publicly viewable, uploading it to archive.org seems appropriate (but don't take my word for it). Though if you do upload, it sounds like just the "part files" or just the "full files" would be enough. You could then also seed the torrent there.
The imgur links you might try uploading to ArchiveTeam's imgur-grab project. Looking at the tracker, the archival seems currently half dead, but I'm sure they'll get around to saving what's left. (Unless it's dead because imgur made it nigh impossible, which I can definitely imagine)
The URLs project plays it fast and loose and archives an assortment of random URLs. This one has an IP block warning.
Some have NSFW warnings.
Other projects aim to archive a single site as accurately as possible (possibly with a deadline when the site is shutting down), so they can't afford to have their warriors blocked or rate limited. If you are, that would be because of an issue. You can choose to archive sites you don't want to visit to avoid issues.
I was going to mention ArchiveTeam's warrior because I thought it wouldn't be listed, since computing isn't really the important thing you're donating, more your virgin IP address and internet connection... but it's third on the list!
If you store it in compressed chunks (or on a file system that supports compression, I guess), that should be a great deal smaller, being text only.
They supposedly never delete good stuff, just make it unavailable, as you said. Maybe we'll get them in a hundred or so years!
ArchiveTeam's uploads also don't have torrent files (anymore). Their wiki says that they disabled it to lighten the load on IA's servers, as creating a .torrent file for a 10+GB upload takes considerable time, especially if it has to be redone.