A load of 2.5 tons for 1225 feet of conditioned space isn't very likely even if there is no insulation in the house anywhere. A 3/4 ton ductless mini-split in the living room and another 3/4 tonner upstairs would probably work out better.
A consultant in the Atlanta Georgia area plotted the square feet per ton against house size for dozens of Manual-J load calculations done for clients to come up with this graphic:
Note that even the WORST performing house in the sample was a ~1500' house that came in at a ton per 600', and that's in the steamy hot & humid south where many houses have no insulation and are fitted with single pane windows/no-storms, not Westchester County New York.
Before going any further you may want to do your own Manual-J using the fairly simple but reasonably accurate
loadcalc Manual-J tool. It tends to overshoot reality by double-digit percentages unless you pretend the house and ducts are all very air tight, and it doesn't have a lot of nuance for the shading factor inputs. Run separate load numbers for just the upstairs and just the downstairs, since it usually is more comfortable and efficient to zone it by floor.
For the locations on the loadcalc pull down menu list the closest to you are NYC/central park, and White Plains, but the cooling load numbers won't be very different selecting one vs. the other- there will be a bigger difference in the heating load. The 1% design temp for Central Park is 89F, to White Plains' 87F.
Oversizing the AC results in lousier humidity control- bigger is definitely
not better in a summer climate as sticky as yours.