Here's a chassis dyno of a Roush 427R
Here is a chassis dyno of a Roush 427R crate engine, as installed in a Superformance. They have installed many of these 427R engines in cobra's, and this is the best output any of the 427R engines had made. They are rated by Roush at 550 HP and 535 torque at the flywheel. The engine was not run above 5800 rpm's where you would expect to see max HP, but the max torque is a good value.