I'm going to have a replacement steering box and coupler installed on a '63 A body and wonder how much labor, in terms of time spent. it will take to do that job.

If everything comes apart really easy, it takes about 3 hours in a late A-body with a slant six. A bit less if they have a car hoist.

-D.Idiot

I remember your name from the old /6 dotcom site! Thank you for the reply. There will be a hoist.

Been a while!

Pretty much a steering box change involves after getting room under the car, and making sure it doesn;t roll away):

1) Removing the coupler (roll pin in the late cars, removing the flange bolts in others, etc...). They may need to unbolt the steering column to pull it back a bit (3 bolts on the floor, bezel and 2 nuts and washers under the dash.
2) removing the pitman arm at the box (may need to remove the arm from the steering link depending on year and play in the link.
3) removing the 3 bolts holding it to the K-member
4) install in reverse making sure to clock the replacement box to the alignment of the wheels, and making sure not to trash the inside of the car putting the column back in place.

-D.Idiot