Yep and I think there's a good possibility that Ingo would get lucky, since Moore's chin was good but not great at heavyweight.
Pick somebody from here As selected by The Ring magazine in the February 1956 issue. Heavyweights, Rocky Marciano, Champion Archie Moore Bob Baker Tommy (Hurricane) Jackson John Holman Willie Pastrano Nino Valdes Johnny Summerlin Bob Satterfield Young Jack Johnson Ezzard Charles
Valdes--I don't would think he should be in this. Yes, he had lost twice to Moore. He had also lost twice to Baker, and also to Satterfield, twice to Machen, once by ko. I would assume he wasn't even in the top ten by the summer of 1956. By the way, and this has been gone over many times, I don't think he was ducked by Marciano. LaStarza was the #1 contender in 1953. Valdes wouldn't accept an elimination bout with Charles, so Charles moved up to the #1 contender position in 1954 after ko'ing Satterfield. In 1955 Valdes lost an elimination bout to Moore. Granddad Moore--He was the best out there, though. Just like today you would have to beat the 41 year old Vitali or the soon to be 37 year old Wlad to be the top man. *as for the original question, I think Eddie Machen would have been the next best out there.
As near as I can figure from an article printed about 8 days before Marciano retired, the press was already speculating on what happens if he retires, which was being mulled over at the time between he and Al Weill. The article was pressing Promoter (IBC) Jim Norris on what happens and Norris was hoping Marciano would not because he was going to produce a $500,000 gate for Marciano later in the year. However, he was talking about trying to make Patterson and Hurricane Jackson for September and the winner of a June meeting between Johnny Holman and Bob Baker (won by Baker). The writer also speculated that Archie Moore after he defends his title against Yolande Pompey would still be in the picture (Moore fought 8 times in the heavyweight division since the Marciano fight and before Rocky announced his retirement). Jim Norris also stated therre was a number of fine young fighters coming up that were promising. He named, Willie Pastrano, Johnny Summerlin, Eddie Machen and Sonny Liston. But looking at results, it does appear that Bob Baker should have been the 4th man. He had recently beaten Nono Valdez, lost a verrrry close majority decision to Hurricane Jackson and then beat Johnny Holman. Don't know why they didn't just make it a clean 4 man tourney.
The 4th man could have potentially been Harold Carter. He had some good wins around this time and he and Summerlin fought a bout billed as an eliminator.