Still haven’t heard an argument that convinces me that using hp is a good idea. There are better methods. Your idea of using factory hp numbers is good, but it does require knowledgeable judges and registration people. Plus hp ratings changed almost every year. Let’s just leave hp out of it. If the show is bigger and needs to broken down more, there are better ways. Mopar, Mustang, Corvette, Camaro/Firebird classes. If you must, maybe a simple big block and small block classes. Convertable and coupe classes. Horsepower has it’s place, but it doesn’t do anything for how well a car shows.