Clevelands were consider big blocks by some folks due to the fact that they delivered big block power but it's still a 351cu...
Back in the days, the best 351C was the one built by the Aussies.
They used it in their Ford Falcon XB/GT (Mad Max car) with their own special heads which was a cross between the 2V and 4V scenario.
Later on, Edelbrock made a nice aluminum set of heads similar to the Australian ones but in the end, a stroked Windsor like the 408 or 427 is the preferred way to go.
Cleveland blocks are heavy and have a tendency to eat cams due to poor oil delivery but that mill would always outdo the Windsor no matter what. The torque alone was an obvious difference.
And as a History note, the 71 Boss 351c was the fastest Mustang ever produced until the 2000 Cobra R...