Don't know what vehicle you are talking about but as Britcon says, sit in seat with mock up column/wheel, mount/mock steering box, figure a couple of ujoints and connection bar and should give good idea. Seems like you would want just enough to stick thru firewall so as to get minimum angles down to box. But if it's aligned, not a big worry. I have done this before but I already had a column and the got the box and ujoints and bar to mock it up. Cutting a stock column can be done but I don't think that is what you are asking how to do. you can't go too much by others unless they have the same column and truck and box and wheel.
