Is 426ci 360 a small block?

I had 40 plus pulls to 6,600-6,700 rpm. Less than 24 hours later he bends a valve.

I told him, "This will rev faster and pull harder than you can believe. It won't stop winding and you don't have a rev limiter. You are the rev limiter at this point."

It leaves at 2% leakdown and comes back at 55% leakdown.

It won't leave here again with a right foot as a rev limiter.