Good point. I didn't think about the fact that when a cylinder pulls it has less surface area for the pressure to push against due to the rod. So you do have to go bigger to get the required lift. Thanks for the correction. Shock is another consideration.
A 1 inch rod reduces surface area by 0.79 square inches. So a 1.5" cylinder with a 1" rod would exert 1.77 x system pressure on the push stroke but only 0.98 x system pressure on the pull stroke. So with 2000 psi you get about 2000 pounds of pull.
The list below gives an idea of how much weight you will be able to tilt up with different cylinders at a distance behind the links that equals the distance between the link attachment points. This doesn't take changing angles into acount and assumes a right angle between the cylinder and a line drawn through the link attachment points. In reality, you will get a little less than these numbers because you wont be at a perfect right angle.
A 1.75 inch cylinder with 1" rod gives ~3200 pounds of pull with 2000 psi
A 2 inch cylinder with a 1" rod gives ~4700 pounds of pull with 2000 psi
A 2 inch cylinder with a 1 1/8" rod gives ~ 4300 pounds of pull with 2000 psi
A 2.5 inch cylinder with a 1 1/8" rod gives ~ 7800 pounds of pull with 2000 psi
A 3 inch cylinder with a 1 1/4" rod gives ~ 11,700 pounds of pull with 2000 psi
Since your 3pt is rated around 2500 pounds, if it were my tractor, I would probably go with the 2 inch bore, 1 1/8 inch rod. I would get one that could handle a 5000 psi shock load which would equate to over 10,000 - 15,000 pounds depending on the direction of the shock load.
If I went bigger, I don't know if I could restrain myself