While both 30 footers the Cal 9.2 and the C&C are quite different beasts.
The C&C is a good all-round cruiser/racer, well recognized in North America (and in Europe as a "Trapper") and plenty of them have been built. They are available in both gas engine models and diesels, as are many of the 70s/80s boats.
The Cal is a smaller, lighter IOR influenced design and it will reward you with better performance when well handled (esp upwind), but will likely be somewhat more tender and less forgiving overall. They are a nice looking boat, a Ron Holland design and he had some major successes in his career.
If you intend to do a fair bit of club racing the Cal may prove more suitable, but the C&C will make a better summer home for cruising. Of course both boats can do both; it depends on what your main priorities for use will be.
Outside of these comments, I'd suggest you don't get locked into either of these at this early stage.. get out and do the dock walks, look at all sorts of boats and try to get some time on the water at a local club to get a feel for the differences between boats. Local race crews are often shorthanded and many skippers are happy to introduce new people to the sport. Be reliable, listen and learn and you'll be invited back. Sailing OPBs (other peoples boats) is definitely the most economical way to do this....
Best of luck...
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)