Since its release in 1981, there have been huge library of Call of Cthulhu scenarios and supplements. We don't want all these great classics to go away and are working to bring back as many as we can for you to enjoy. Many are currently available only in PDF format, but we are working on that as well.
Can we use them with 7th Edition?
Absolutely, the 7th Edition Keeper Rulebook has a very short section dedicated to this as almost every conversion can be made on the fly. If you are new to the game I would start with the 7th Edition scenarios, but when your players come clamoring back for more feel free to go into the Classics as well.