The Ruby Ray Mystery

In the series, this is a straight up spy story.
Pretty updatable, but several scenes would be removed as they wouldn't need to arrange a flyby of the chateau, just look at satellite photos. The wouldn't need to get a kid to buy train tickets, just buy them on the phone.
Also, as in other of the books, the Megabuck network wouldn't be as needed, they are replaced by phones.
A pay-as-you-go phone could be used to track the cars.
I understand that climbers use cams rather than pitons these days, so the worries about noise during the climb would be less.

The renting of a very expensive sports car (Mercedes 300SL, now selling for millions) seems unlikely.

A couple of plot points would have to change.
The Anti-Communist stuff and the ACTION group would have to change as the Soviet Union is gone.
Also, using lasers in surgery isn't unusual enough to warrant the plot.

I enjoyed the story a lot, it showed off how clever Rick and Scotty have become.