All these Cal 20's popping up lately in need of rescue...makes ya want to join the fire department just to get a piece of the action!
You lucked into a great boat that is not only very seaworthy but known for having a turn of speed. OK, that covers it from your perspective and your son's desires. (g)
You'll find quite a bit of info on the 20 in the Cal forum here and you'll also find that they're actively raced on the west coast so there are quite a few people out there keeping these good old boats going. As far as fixing her up goes...you're in luck, as we have one of the greatest ever fixer-up threads on just your boat. Look here and then decide what parts apply to your boat:
Cal 20 Restoration Set 1
It's from this thread and Jim pops in from time to time here:
Cal 20-- Excellent Starter Boat