I think that our view on how things are and what they look like in Kirks era and before has to default to what we've seen in the JJverse UNLESS it has been established in TV or in novels to be otherwise. For instance London in the 23rd century...
I would say that as we have already established an actor for Pike on TV, the one in the novels is Hunter.
I suspect that's up to the reader to some degree, like whether you visualize Saavik as Kirstie Alley or Robin Curtis.
And if somebody wants to visualize Chris Pine or Zachary Quinto when reading a TOS novel, who are we to object?