Actually, strips themselves are a pretty serious pain. Comic books are periodicals, so we can look for issues by year and title. Comics strips are "contributions to periodicals" (every single installment, by the way), so they're looked up by year and...copyright holder. Creator? Artist? Home newspaper? Syndicate? Some homeless dude standing on the streetcorner ranting about the nigh-ness of the end of the world? Maybe.
And if there's no copyright statement on the script, it's in a bunch of periodicals. Are any of the newspapers still under copyright? I don't think anybody has given much thought to whether the paper's copyright would extend to a contribution like that, but I wouldn't bet against it.
Plus, while McNaught isn't around anymore (they folded in the '80s), they handled a lot of high profile properties, like Dear Abby, Dale Carnegie, and Heathcliff, making copyrights likely something they handled well. That's not definitive, obviously, but the effort involved in the research combined with a probable result makes most strips a low-priority search for us.
