First thing to do would be to ask this question on the 9N, 2N, 8N discussion forum
on this same site. Those folks have lots of experience dealing with the lift system on your tractor. Click here
to get an adjusting jig and pamphlet of tips and tricks from Zane Sherman. You can read an unsolicited testimonial to the usefulness of Zane's jig by clicking here
As for the lifting capacity of the lift, don't worry about it. The front wheels will come off the ground before you ever overtax the hydraulic system.