new power steering hard to turn left turns right great

[68SPECIAL]

I recently did a ps conversion to my 68 F250 camper special. 390 motor, 4sp tranny, no ac.
I changed the drivers side motor mount, steering box, pump brackets, pump, firewall brackets, and steering shaft from a dentside. dont know exactly what year. The pump was bad so i bought a remanufactured one. There is an s shaped ps cooler near the frame as well. I got everything bolted up the other night.
The box i removed from the donor truck had some rusty fluid in it. I drained it as best i could and and installed it, connect all lines except the return line to the pump and turned the pump by hand while filling with ps fluid until all the crappy dirty fluid came out of the return line and i saw clean new fliud. Then with the truck on jack stands and ps belt connected, i started it up and turned the wheel back and forth for a bit and toppped off with fluid as needed. I turned the wheel straight and it started to turn to the right side progressivly quicker the further it went. it did that everytime i straightend the wheel, it would turn left but was much more difficult. i dropped it from the stands and took it for a test drive. it works great when i turn right but is still hard to turn left (although its easier than it used to be with no ps). I drove about 10 minutes and pulled over to check things out. when i popped the hood the pump and lines were VERY hot. much hotter than the radiator hoses but not quit as hot as the manifolds? is that normal? is the box bad? I am thinking its the box because it had the rusty fluid but dont want to by a new one if i dont have too. anythoughts?? my main concern is the the difficulty it is having turning right and if this is the reason that its getting so hot?
thomas

[68SPECIAL]

one more thing, when i checked the fluid after the test drive is had a milky white tent but was not very noticable. I am replacing the fluid with type F this week and will see what happens.

[fordman]

the box is probably dirty and sticking the ball inside of it. it probably needs to be cleaned up inside or rebuilt.