Re: What did I screw up???
Personally I would just remove the rest of the back drive linkage that is bolted to the frame and the rod that goes up to the lever at the bottom of the column. Why it affects you getting it out of reverse is beyond me because the linkage that runs from the back drive linkage to the transmission is already gone. I would then turn the column sleeve all the way to the left and leave it there. On my car I have a jumper wire running between the connector where the two larger purple wires are on the lower column. You have to be careful to always dump the clutch with that setup because you can start the car in any gear. I would then mount a switch on the transmission linkage for the back-up lights and run wires from the other connector on the lower column to that switch. I would then check all the bushings on the transmission linkage and replace them with the metal ones then check any bolts or nuts on the shifter body itself besides where all the linkage plates that bolt to the transmission for tightness and then check the linkage for neutral alignment at the shifter itself. If you still want to mount your tach on the column you can just make sure the collar is all the way to the left and then tighten the band clamp. Do not overtighten that clamp because you could distort the collar.
71 Malibu, Cottonwood Green, 396 BBC, AutoGear M22W 4 speed, 12 bolt 3:55 posi.