Truthfully the 110/80-18 will fit your newer rim better than the 120/70-18 does.... It will have a broad rounded profile akin to a softball so the steering response will be just a little heavier but the bike will roll more naturally into the corners verse falling into the corners that the pinched 120/70 profile causes....
Tire looks like it will not make a long trip.
Check date code on 110 and don't use if it is older than say 6 years, 7 max.
I change mine if they get over 4 years old. Is that too soon?
Well with the way you keep riding around in circles I'm sure they don't last much more than 4 hours...... LOL
Now I would say that depending on how stored I'd have no qualms about an older tire that was kept in a cool, dry location that was not exposed to direct sunlight....
That's good because I just installed what may be the last new set of Michelin Pilot GTs in existence. They've been in my cool, dark, semi-dry basement since 2009. If they blow up and kill me, my fiancé will post up an ad: "Parts bike for sale. Some road rash."
Not the last set, I've got a set in my basement too.