I have tried most every type of clutch. The very best was an original 10.95 440 clutch and pressure plate, but it was too stiff and broke things. I'm afraid my best 273 iteration was way over 300 hp at 6,500 rpm. I do have a McLeod 105 BB/Long setup to try with next engine. Not a fan of ceramic metallic clutches or diaphragm pressure plates and have tried them.