Plenty of archivists out there and infinite ways to archive, anon. Here's one way, wrote it just now. Not endorsing and not what I use, purely for illustration:
curl -sA https://8ch.net/qresearch/threads.json | jq ".[].threads[].no" -r | xargs -n 10 -I {} curl -sA https://8ch.net/qresearch/res/{}.json | tee output.json
To also archive the post images, post-process and pull out the "tim" + "ext" fields and "extra_files" field. You'll also have to grab the embeds which is another step. Have fun!