the R&R procedure is found in factory service manuals. If I don't want to pull the park brake lever and work around it, plus I know I'll need to move the shifter to neutral, I chock the wheels.
Knowing a little about how it was all put together can help discover shortcuts. On the assembly line the complete dash, inst' panel included, was placed in the car. To do this, the steering column was still MIA. That means you'll need to at least lower the steering column. ( Please note; If you have column shift, remove all the column mounting hardware so the column lowers enough. Be gentle. To pull down on the column with any force will disturb shifter linkage and neutral safety switch adjustment. Gently move the column back up in place where it was before so no disruption to signal switch, horn switch, etc., occurs. )
Then there is the electrical wiring and speedometer cable. Factory had the wiring included with the dash assembly so all they needed to do was poke the bulkhead connection through the square hole in the firewall from inside out. Someone else would attach the 3 connectors outside. So.... want a lot more slack in the wire harness to work with ? the bulkhead connection can be taken apart in 5 minutes or less.
They also has a lot of extra speedometer cable length inside. Once the dash was in place the extra length was pushed out through the firewall grommet so someone else under the car could secure it under bent metal strap welded to the floor under the drivers seat area. So... if you were to unsecure the speedometer cable there, you could shove extra cable length into the cabin. That is one thing that I always do even if I choose not to feck with the bulkhead connector.
The speedometer cable is the last thing I disconnect from the inst' panel. When I go to reinstall the panel, attaching that cable first provides a fairly strong tether/support while I attach the wiring, etc...
I cant remove a seat by myself. I sit in it while working. So start with the info from the service manual, then consider our methods to the madness. You'll find what works best for you and what you might do differently next time. Have fun