BoxRec

That would have been a very attractive fight. It would have done extremely well at the gate.

Why didn't it come off?

Maybe it didn't materialize because Johansson remembers being embarrassed by a teenage Clay just a few years earlier during an infamous sparring session in Miami.
By September '63, Clay was world ranked and just months away from becoming champion. I doubt the Swede really wanted any part of Clay by then (money aside).

Patterson poleaxed Johansson twice in the previous 4 years. Clay wouldn't have had to wait for the Swede to tire. He would have had him out early too.
Don't know for sure if the sparring session was legit or a stunt. Experts on both sides have always debated it.
It must be part of that pesky Ali Myth Machine I keep hearing about.

I gotta figure it would've been a one-sided fight with Ali winning with his jab and movement and probably taking out Ingo in the 5th round or thereabouts.