[quote="ArticIngerCase] I ran the hoses to the PTO but I altered the PTO valve "doors" so as never to give full power to the cylinder. That could be very, very dangerous if the cylinder bottomed out with the full pressure of the PTO behind it[/quote]
I'd like to amplify Scott's points for anyone planning this mod, in any device that has a hydraulic cylinder the cylinder should be able to move the full length of it's stroke and bottom out before the part being controlled reaches the end of its range of movement. In other words, the plow should be able to swing as far as the cylinder will move it without hitting any stops otherwise the power of the cylinder will likely damage the joint or structure. So, measure carefully before you start welding things together. You can also set the pressure relief lower to avoid overpowering the joints but you never know when someone might "reset" it. A hydraulic cylinder can be deadheaded safely up to the pressure rating of the cylinder so you're not going to blow it apart unless you exceed the design rating.
Aside from the issue of overpower the joint, you want to be careful to limit the flow so that the cylinder doesn't move too quickly as it would if given the full flow of the pump. I'd probably make connections using 1/4" lines as that would limit the flow to the cylinder to a reasonable rate.