Other than sealed bolts, valve covers and oil pan seems the CT is just a ZZ4. I broke a valve spring on my original Lt-1/Zr-1 engine that we (MountainMotor, Curtis) and I built in '02. It lasted 30k and lots of 1/4 passes but is also .40 over with 1 sleeved cyl. Car had been raced in the '70s...