I needed to retrieve the real contents of (http://pdp-10.trailing-edge.com/bb-x141b-bb/index.html)[some text files on Bitsavers archive]. I wasn't willing to go figure out TOPS-10 BACKUP tape format and fiddle around, although I admit I did try that path at first.
This is the solution I came up with. I like Javascript. It's expressive!. This took about ten minutes to put together counting the "learning curve" for (https://cheerio.js.org/)[cheerio].