He would clearly be unranked, but at the time, I doubt that he would have been a worse title challenger than Harrison or Chisora. Perhaps Finegan is a model of how low we have fallen recently?
Just a note here: many historians are still debating whether or not the John Finnegan bout was a true title defense at all. Some insist is was a mere exhibition that got out of hand when Finnegan saw an opportunity to go for the gold and attempted to take Jeffries out, which cost him dearly. I'm still looking into it myself. Anyone have a primary source report? I have read Pittsburgh papers and there is no reports of Finnegan- who appeared in print often- "training" for a "title shot" at champion Jeffries. Surely something like that would have been in Finnegan's hometown papers somewhere, right?
I think he would be considerably worse than either of those you mentioned with his being 60lbs lighter than Jeffries, and having been ko'd by Ruhlin 4 months earlier, being dropped 8 times in the 4 rds the fight lasted.