The steering column when disconnected from the steering box input can be twisted - and it's positioning can be "straightened" by pulling it off and putting it back on straight - there is no indexing mark on that steering box knurled shaft. However, if the column shift linkage is working well now, reclocking the column may possibly/likely result in linkage from the column shifter to the transmission binding and/or being out of whack. It's possible that the shift cable in the engine bay that connects to the lever that pokes out of the steering column, and goes down to the transmission connection has been replaced with an incorrect length one, or something like that, and the fix was to clock the column to make it work. 1965 transmissions were cable shifted.
Once you ascertain if the shift cable is OK, then you can proceed. If not, wait and get the right one.
Here are the basics - others, please chime in if you see that I've missed any steps.
Park the car with the steering wheel in the straight position.
There is a plate on the floor where the column goes through - there is a collar, and a bigger plate. Plate should be loosened, collar bolts removed and slide the collar up the column a bit.
Remove the bottom cover of the dash under the steering column. It's big and clumsy... but it should lie on the floor sort of out of the way while you continue.
Disconnect the shifter readout (in the guage cluster) linkage under the dash - and keep in mind that you will have to reset the linkage adjustment under the dash once your reclock the column. It is quite fragile, and is easy to break it if you don't know it's there.
There is a collar under the dash holding the column up in place. That should be removed - support the wheel with something on the seat so you don't put stress on the rubber coupler at the firewall (found under the round heat shield by the driver side exhaust manifold).
Remove the roll pin at the steering box where the column connects. Mark the box AND the column for reference BEFORE YOU REMOVE THE COLUMN FROM THE BOX.
Carefully push the steering column off the knurl at the steering box. Go slowly, and do not force things as the lower coupling can come apart, and you can bend or jam up the column shift linkage and pinch or kink the cable.
Once the column comes off the steering box, reposition the column, and keep the wheel in the straight position before pushing it back onto the steering box knurl.
Push the column back onto the knurl, and reinstall the roll pin - preferably with a new one.
Button things back up - dash column collar, shifter readout linkage, floor plate, lower collar at the plate, yadda yadda.
REMEMBER - you need to find out WHY the column was clocked in the first place - I suspect you've got the wrong shift cable installed there (possibly a B body one). The steps above WILL NOT WORK if the cable and linkage are incorrect.
