This is a tough one to pick. Either one has the ability to take out the other. Spinks was a great Light Heavyweight - his 'Jinx' could take out a guy with one shot, or he could box his way to a tactical decision as in the unification bout with Qawi. As a heavyweight, his blowout by Tyson showed that he was vulnerable to a heavy puncher. Patterson's bouts with Liston were eerily similar. Since the thread stipulates for the heavyweight championship, I will lean toward Floyd based on his longer career and more solid resume as a heavyweight.
Spinks UD. He was bigger with a longer reach than floyd and had the ring savvy and movement to avoid his punches and connect with his own flurries.
A good match for sure. But Floyd was so fast & skilled, I do not see Spinks avoiding most of his shots. If not a slugger & a moderate sized HW, Patterson has a great shot against all but the very best champions.
50/50 for me. Spink's prime was at 175. He did ok at heavyweight, but there are too few showings to make him a definitive favorite. Both men have a good shot.
I like Patterson inside the distance. Spinks arguably lost the second Holmes fight, beat a pathetic version of Cooney (not Spinks' fault of course) and a forgettable fighter who is now a promoter - Stephan Tangstad. Both failed miserably against Liston and Tyson respectably. Patterson's heavyweight resume' was impressive and I believe he would be too much for Spinks, who was also a fine fighter but did the lion's share of his best work at LHWT.
I see Floyd's speed troubling Michael for the first half of the fight, but Spinks tagging him hard in the later rounds and taking him out, or at least dropping him enough times to take a decision.
I'd give it to Spinks. Michael Spinks was a heavyweight who cut weight and fought as a light heavyweight. Floyd Patterson was a light heavyweight who put on a little weight and fought as a heavyweight. Both are really good boxers but I think that Spinks' size would tell. He doesn't carry a lot more weight than Patterson but that 6" reach advantage and 2 1/2 inches of height should trouble Patterson like the times he fought Ali.
Intriguing fight. I choose Floyd. Speed would be the factor in this one,I think,and Patterson would get the big punches in first