I'm still searching. Here's one writeup I found.
My '65 has the long shaft. In replacing the box with a FR box, I removed the drivers seat, the steering wheel, the column sheath, the left shock tower brace, the z-bar clutch linkage, spark plugs and the left header, the left valve cover.
I pulled the Pitman arm using a clamping puller. A bungee was tied around the old box to keep it from falling and the frame bolts were removed. While holding the box the bungee cord was removed and the box rotated slowly and brought upward as my helper held the long shaft from hitting anything in the interior. Rotating the box while bring it forward and upward along the left shock tower. It was a tight fit but it came out and the new one was installed in the reverse sequence.
If you have a power brake booster in the way, this likely wouldn't work without also removing the master cylinder and power brake booster.
To avoid all this, it is possible to remove it from the bottom side if you have the car on a hoist. In this case, removing the tie rod and engine crossmember is required. This allows you to go down and out rather than up and out.