Contrary to popular belief, Conn wasn't as elusive as people say he was. In fact, he mixed it up a lot on the inside against Louis which is what got him knocked out in the end. He was very shifty and technical on the inside mind you, but the Rock was just too strong and fierce to not catch up to him at some point.
I think Marciano's lack of textbook technique would serve him well here. Louis for all his marvelous technique didn't surprise anybody, they just couldn't hide for 15 rounds. Marciano's punches were off rhythym, came from strange angles, and targeted non traditional areas. Marciano is all wrong for Conn.