It is not likely you will find a puppy from properly health tested parents that easy to find. You will see cavalier puppies advertised for sale but even show winning cavalier club breeders will often be unable to show you the complete set of current Eye, Heart, MRI and DNA certificates. Many of them will have mated one or both parent when they are too young for any test results to have any significance.
If you wish I can email you some detailed Puppy Buying Advice which has a list of breeders that have said or written that they MRI scan their breeding dogs and that they do other health tests. My article will give you some idea how to identify and read the certificates. The list of breeders ( who may or may not be telling the truth ) will give you somewhere to start your search.
Cavaliers......Tommy Tuppence 2000-2012 and a half share of Faith.
Japanese Chins.... Dandy, Benny, Bridgette and Hana.