By landing Ingo's Bingo the punch that Carnera was highly susceptible to.Johannson could whack with that right.
It has to be noted that Carnera was susceptible to the right hand and this is part of the reason why Max Baer gave him such a good hiding. Baer for all his clowning esentialy fought a tactical fight. Of course Johansen was not as durable as Baer and wasnt as dangerous in the later rounds so Carnera might be able to outlast Ingo and take control of the fight.
Its hard to tell how dangerous Ingo was in the later rounds because he rarely went into them ,but he kod Franco Cavichi in 13rds and Joe Erskine in 13rds so I guess he was pretty dangerous.
Ingo would drop Primo, but not keep him there. Carnera was not prone to losing his senses like Patterson sometimes did. Sharkey dropped him with a bomb of a hook in their first bout, yet Primo immediately got up, then had the presence of mind to immediately get down to one knee to take advantage of a full count. Pulling Max Baer down with him was a shrewd time buying tactic. Stepping on Loughran's feet was a clever little dirty trick for slowing Loughran down. This one goes the distance. If it's scored on a rounds basis, Primo takes it. On points, I figure it's a toss-up, depending on how many knockdowns Johansson can register. Carnera's ankle was injured early against Baer. Presuming he suffers no such injury with Ingo, I think Primo takes it. Johansson had a habit of continually retreating to draw his opponent into his right. That would backfire here as his upright European stance would leave him on the end of Carnera's pesky long jab. Primo could also retreat behind his reach against somebody Ingo's size. Carnera would be busier. In close, he would be using his weight and strength to lean on Johansson to tire him as the bout progressed. Primo had a bigger heart and better conditioning, as he was more proven over 15 rounds. Ingo's best shot would be to halt him as he did Patterson, with early multiple knockdowns forcing a stoppage. However, Baer could not do this, so I doubt Johansson would. Carnera W 15 PTS Johansson
If Carnera is mobile a foot like I've seen in some of his fights he could win a decision. If Carnera tries to exchange with Ingo flat footed he could get caught with Ingo's power right which could hurt him. Carnera did not respect Baer's right hand which was a big mistake, especially because he walked into it increasing the power effect.