If it were me, if my truck had issues shifting in the normal fashion and it was more like a combination lock, I would just drop in a bone-yard column with tilt. It will probably be easier to find the right levers if they break and you have they added feature of the tilt wheel.
On every square body chevy truck I have owned or worked on, issues with columns were rare but when you had one it was really difficult to properly fix one. The key cylinder for the ignition, the cancel cam for the turn signals and the horn button are the probably the most common to fail on any GM column, but when you have a lever or rod that is out of alignment causing shifting issues , it is often very hard to correct, at least from my experience.
A junk-yard column will probably set you back $100 - $150 complete and take maybe 3 hours to change out, if you have problems. The only issues from my time turning wrenches with tilt-columns is the tilt comes loose from use over time, but it is fairly easy to fix.
This may make things much easier then trying to trace out why the key won't turn when it's not in gear.
Good Luck man.