That's actually a pretty fascinating matchup--I think Norton has a legit chance due to both his size and significant reach advantage plus his unorthodox style--(which would neutralize the Rock's power.)
Being under 35, having had less than 90 fights and being a natural heavyweight might neutralise it a bit too.
Norton has a chance due to Marciano being a bit of an unknown quantity against notable Heavyweights over 200 pounds minus an ancient Joe Louis. Norton said his walking around weight was about 230 pounds and he could weigh up to 220 pounds in fights which is a significant size advantage over Marciano especially being 6'3 with 80 inch reach. But despite Marciano being smaller I still think his relentless aggression is a problem for Norton who's chin may not be as bad as people make out but his recuperative powers are probably below average. s so if Marciano hurts Norton then I don't think Norton has the survival instincts to overcome it as he seemed to freeze when he got hurt. There's pros and cons for both fighters but I'd give Marciano the edge here I think he could get underneath Norton's cross arm defence and his smaller height may be an advantage in that regard. I also think he punches too hard for Norton consistently over the course of the bout. Norton can't fight going backwards has poor recuperative powers.