First, I am NOT a fan of loader mounted blades on small tractors. I built one and had terrible steering problems with it. Due to the geometry of the loader and where the pivot point is (up high), whenever the plow meets resistance the front wheels will come off of the ground. You can see this for yourself by floating the loader and driving into a dirt pile...what happens to the front wheels?
Now, you will have two choices for a new circuit to operate the angle cylinders:
1. You can add a new spool valve, fed from the Power Beyond circuit and extend hose up the the front. I believe JD now has a factory option for a third SCV-unsure of the cost. But you would still need hoses form the QD's on the rear extended up to the front of the loader.
2. You can add a "diverter" valve, that effectively "splits" the dump/curl circuit (joystick left/right) into two separate circuits. Basically there is a momentary switch thats mounted to the joystick, when activated the left/right motion of the joystick controls the angle cylinders. This opting will be about $500 and require you to source all the parts/fittings and make the mounts.