The obvious answer to "are these any good?" is to listen to them yourself and decide. You already paid for them, after all!
Taking them in reverse order: The Van Cliburn disc is one of the biggest-selling classical recordings ever. It was made just after Cliburn won the Tchaikovsky Competition, making him an instant celebrity. (Yes, as strange as it may seem now, fifty years ago, the Tchaikovsky Competition was as big a stepping-stone to stardom as American Idol is now.) In any event, this was Cliburn's first recording, and made it on the Billboard Album Chart (that's for popular albums, by the way), where it remained for several years.
Now, I notice that your disc has an LM- catalog number. That means it's mono. (Stereo RCAs had an LSC- catalog number instead.) In other words, it isn't going to be an audiophile spectacular, but it won't make the performance any less excellent. And, look at it this way: if you like the performance, you can always get the SACD and enjoy it in three-track.
While I'm not familiar with that particular Karajan/Mozart recording (HvK recorded virtually every major piece several times between the fifties and the eighties), from what I recall of his later EMI recording of the late Mozart symphonies, the critical consensus was that he took an overly heavy, old-fashioned approach to Mozart. Still, I'm sure the musicianship and ensemble on the recording will be great, since Karajan was a perfectionist in those areas, and you may find the older, more "romantic" Mozart to your liking. While I don't know who produced and engineered those discs, Decca/London "bluebacks" had a reputation for sound almost up there with Mercury and RCA at that point, with producers and engineers like John Culshaw, Charles Gerhardt, and Kenneth Wilkinson. So, odds are that the sound quality will be at least acceptable and possibly a great deal more than that.