There was a couple guys out in the black hills that did a T speedster five or so years ago that put them on a mopar axle. Used the Ford wishbones too by putting some sleeves in the axle. So i know it can be done. Not sure how much machining it requires. I think they had to have the axle bent by a frame shop to get the right camber.
You have to ream the king pin bung. I don't recall the size. Maybe contaqct benD here on the HAMB he has one he had reamed to fit the ford kingpin.
Porknbeaner hit it right. The tube axle king pins are slightly smaller then the Ford's king pins. I used to suggest doing the reaming on a verticle mill. It can be done in your garage with a adjustable reamer. Some people say the the king pin angle is different from a Ford I beam, but a truck alignment center can take care of that.