Sizing for 1400 square foot house

My mother in law in central GA needs a new system. Her current condenser is a 26 year old goodman 3 ton.

We had 1 quote and the salesman strongly recommended we stay with 3 ton since that's the system we had before even though the house is 1400 square feet (he said he counted 1700 square feet). I wouldn't necessarily mind the 3 ton, but appears the "line set" is 1/2 inch and he said it would need to be replaced to put in another 3 ton.

My mother in law can't recall if her system short cycled before and I never noticed one way or another. I think the 3 ton may be overkill and I'm confident the square footage is closer to the 1400 number based on the county GIS and my mother in law who purchased it new in the early 80s.

I guess my main question is there any good reason for her to have a 3 ton over the 2.5 ton? The 2.5 ton would save money, and I assume she can keep her existing lineset, and it would be appropriately sized. Her home is very modest ranch with only a few windows and is brick if that matters.

We have more quotes on the way but just wanted yall's perspective. Thanks in advance