If the engine seems tight, no blue exhaust and no use of oil it probably is a good engine. It was just my experience. After you replace the cat I'm sure there is a shop that can do an exhaust analysis before you go the the death thrones for the state inspection. Florida used to have exhaust check for about eight years in the 90's. It was terminated because the air pollution readings and study's around the state proved that it didn't change. But it was all about money, for the $10 fee the state got $1 and the testing company got $9, however, I know one person (my manager) traded in his clunker because it failed and it was better to replace the car than fix it.