Old Stuff, I mounted a power steering box off of a '7? Ford LTD on a Minneapolis-Moline 'U'. It has enough strength to steer that tractor nicely. The unit has been on there without trouble for at least fifteen years. There is only one drawback,---- it turns the wrong way. I noticed it early in the test-drive. I corrected this with a small gearbox in the steering column, but that might not be cool on a vehicle for the road. So, one thing to watch out for when you are looking through the power boxes, is rotational direction of the steering shaft.
Good luck.