[dsraven]

I think the old trucks are not that structurally strong to hold a steering column outer tube above the floor level, since originally the steering column tube was integral to the steering box so really the floor grommet is simply a seal, so if you are talking about hanging a steering column off the dash and then terminating the outer tube before it exits the floor, and using a bearing mounted to the floor to support the inner column shaft, then that would mean you would need some more structure under the dash to support the weight of it all. then, if you add in a set of dash/firewall mounted pedals and a brake booster you are possibly asking more of the firewall and dash than it was designed to handle. firewall flex means sooner or later something is gonna crack. thats not really good if youre talking about the things that make the truck stop.
a little better explanation of what you mean may help us figure it out though. how would you support the column inside the truck if the column outer tube is cut off before it can be anchored to the floor?