I would pull the whole kit and caboodle. It is about an hour or less if you have had practice.

1. Remove the battery cable from the battery.
2. Pull the harness Connectors on the engine compartment side of the bulkhead connector. Squeeze the tab(s) and wiggle / pull them free.
3. Remove the 2 speed nuts on the side of the bulk head connector (Engine Side of firewall) and if necessary remove the screws that hold the bulkhead connector to the firewall.
4. Disconnect the Vacuum / multi-hose connector and the cables from the A/C Heater Controls under the dash.
5. If you have Vents with cables attached to the center of the dash under the ashtray remove the screws and let them hang. I put the screws back in the holes they came from.
6. Pull both kick panels and disconnect the door jamb wire switches & the Parking brake switch.
7. Disconnect the rear harness connector(s) located under the drivers side kick panel.
8. Disconnect the dimmer switch wiring at the switch. Often it is melted to the switch so it may be easier to just remove the screws holding the switch to the floor.
9. On 70/71 E-bodies with the under dash trim panel I prefer to remove it from the dash so I do not break it moving the dash around. Several screws along the panel and the wire to the map light are all it takes.
10. Under the passenger side of the dash remove the wires to the blower motor resistor from the resistor.
11. On some models there is a A/C duct that runs under the column, remove it. For the 70 E body there is one screw at the end and one near the middle. IIRC It will slide off the AC box duct.
12. Disconnect the taillight Brake light switch located at the pedal assembly.
13. Pull the clutch pedal switch wiring connector if you have one.
14. Pull the flasher unit on the side of the brake pedal support or disconnect it.
15. Pull Steering column completely or at least drop it down:
a. Detach any shift levers (Column Shift or 1970 Interlock linkage) from under the hood
b. Disconnect the Wiring Harness connectors under the steering column.
c. If you are removing the column rotate the steering wheel so you can get a punch in place to drive out the roll pin in the flex connector at the steering box. To separate the flex joint from the steering box I use a pickle fork to PRY- DO NOT HAMMER the coupler loose.
d. Unbolt the lower support at the firewall. The three bolts to the outside of the large semi triangular plate. Do not remove the 2 at at the very bottom of the column that bolt to the small plate to the large plate. It won't hurt but it won't help.
e. Unbolt the lower support under the column so it drops down. There will be some long studs with nuts and wired washers on them, these are the ones to remove.
f. If you are removing the column wiggle it out of the hole in the firewall, otherwise let the column drop down. as far as it will naturally go.
16. Remove the 4 bolts at the top of the dash at or neat the defroster ducts. Sometimes you will need to remove a speaker panel (71 and later B-Bodies) to get to the bolts.
17. Loosen the two bolts at the ends of the dash in the door frame that were covered by the kick panels. Do not completely remove them just back them out about 5 or 10 turns. when replacing he dash sit the dash on the screws and roll it back into place.
18. Place some blankets on a large flat place to lay the dash assembly on for cushioning. Roll the dash towards the rear of the car and lift it out of the car. Place it wiring side up and got to town.

That's from memory so anyone else feel free to chime in if I missed something.

It is so much easier to remove the dash than to fight the harness in the car.