thanks a lot for the math lesson rianwest, probably a great help for the majority of readers, but as a professional with a full workshop, I can handle that much already.
i would point out that you are referring to "rack" based system , not the steering box and arms like the early KE10 etc, which is what i'm dealing with
the early KE10 etc steering arms (the bit that bolts to the ball joint) can't be easily/effectively changed, however i have worked out a couple of ways to alter the idler arm and pitman arm and acheieve what I need. i was really asking for help with swaps to different arms, but it seems that is not possible so mod time, here we come .
thanks again to everyone for comments. i will post a reply once i've got it all sorted