A Nixon blowout.
Smathers would simply not have measured up at the Presidential level.
Nixon/Agnew 400
Smathers/Kennedy 93
Wallace/LeMay 45
Small update added, I gave Nixon Maine as well. The only reason Nixon did not win Maine in 1968 in real life is because Muskie was the Democratic Vice Presidential nominee.
I also have my doubts that Smathers would have carried Florida against Nixon in a Presidential election in 1968. A Senate race, yes, Smathers would have won, but for President, I have my doubts about that.