Do the original Catalina Sails have the Hull number printed on them? I have a 1986 Mod 1 whose sails look to be in good shape. The previous owner didn't know if they were the original sails. Did the original main sail come with the hull number printed on it?
Are the sails crisp or soft? Soft sails indicate they are quite used but they may be fine for day sailing. Crisp sails typically have less usage on them. The condition of the cloth is more important than if they are the original sails as long as they were designed for the boat. Since it sounds like you might be new to sailing, the sails you have now have will probably get you a good start toward learning to sail the boat as long as the cloth is not worn out.