The FWAA vote was not only "legitimate and well respected," it was an official consensus national champion selector as defined by the NCAA from 1954-2013; since the advent of the CFP, their "vote" simply goes to the playoff champ.
In short, Iowa's share of the 1958 national championship is completely legitimate, consensus and official per the NCAA.
You probably knew all that, but since you chose to present the FWAA vote as something less than official and part of ancient history, I thought I'd clear that up for everyone.