I'll check the working length. The TNT manual states top hole of the 3PH for the link.... Tractor manual states bottom for the top link when using the box grader.
With a regular top link that will help you empty the box because it will tilt it forward as it raises, which will 'dump' the box forward a little by raising the rear, making it easier to get the load out and also more likely to clear it without dragging the top back off the pile you just dropped.
I run my power top link in the bottom hole because i generally have more desire for forward tilt than rearward tilt. But i agree that it would suck to not be able to lean the box blade back enough to use the back blade like i wanted to for smoothing.
You can always modify the cylinder you have to make it a bit longer, or you could build a 'spacer' as shown above, or weld an extension onto the box blade itself as well. Multiple ways to deal with it that don't dictate totally replacing your cylinder. But they do all require cutting and welding.