Tiger would arguably be Nunn's toughest opponent. Very strong fighter with solid all-round skills. He could be a bit patchy sometimes, I think, but certainly a tough customer when on form. It's a pity there was no super middleweight division in his era. I'm sure he could have won a title there as well. Nunn as we know was a tall, rangy southpaw with fast hands. Yet, he liked to duke it out sometimes. Generally he was good over the distance. I guess it depends if Tiger can close the distance and get inside. Given Nunn's willingness sometimes to give up height and reach, it may be easier for Tiger than some think. I initially picked Nunn, but actually on second thought I'd give it to Tiger, who I think would be successful enough to wear Nunn down to the point where he's more fighting Tiger's fight than the other way round. Tiger by close decision in a very good fight.
It depends on If Nunn would stay out of range too long, once Tiger had a sense of urgency and the win was slipping he became a different fighter.