Good information above. I have done this swap on my 70. As mentioned, the only difference in column is the center (main) shaft. It "telescopes like an antennae" so that it can collapse during a collision. The "antennae" is held open by two small nylon "break away pins". One half of the shaft is solid (bottom) and the other half is hollow (top).
You can definitely cut down your center shaft. It will be CRITICAL to know the exact length of a power steering shaft. Basically, break those two nylon break-away pins. See if you can push the solid shaft inside the hollow shaft far enough to shorten the overall shaft to the correct length. If not, cut down the solid shaft as needed & slide it back into the hollow half until the overall length is correct.
Lastly, drill 2 holes all the way through both the solid and hollow parts of the shaft, thread the holes, screw in two nylon bolts (plumbing section of hardware store) and cut off any excess part of the nylon bolts so they're flush. Now you just made 2 replacement "break away pins". Re-assemble the column. Done.