It most likely would be better if you installed a rebuilt steering gearbox. Just let the lines drain and run some clean P/S fluid thru them. A good move would be to install a power steering system filter. They are available and are installed in the RETURN line.
A few things to keep in mind, keep the steering wheel locked because excessive movement in either direction could damage the clockspring under the steering wheel.
Also, after filling the reservoir you will need to turn the steering wheel back and forth many times to get all the air out of the system. Just make sure to keep the level in the reservoir as close to full as possible when getting the air out.
If you lock the steering wheel in the straight ahead position and center the steering gear in the center of its travel ,you can feel a high spot when centered, or,count the total number of turns end to end divide the turns in half to get it centered then assemble it you should make out OK.