Prime Marciano vs prime Henry Cooper

Marciano beats Cooper clearly.

A lot has be made about Henry flooring Ali, and no doubt that was an impresive feat.

However we need to take into consideration:

1) Ali was caught just because he was so in command of the fight that he began clowning around taunting Henry, and paid the price for his hubris.

I doubt Rocky is going to be so reckless as Ali.

2) Smelling salts or not, once Ali recovered he went to batter Henry and quickly stopped him.
Marciano was also a tough, resilent fighter; thus unless Henry caught him with a lucky shot, Rocky should win quite confortably.