If the gear box is a '37 or later, hopefully it's a '37-40, the '41 and later are longer. The '37-40 would be a direct replacement for the '35 steering gears, however, you would need a '37-40 frame mount.
I would suggest taking the steering wheel off, removing the front seat cushion, removing the floor mat and floor board section around the column/peddles. Jack up the front end of the and put it on axle stands, disconnect the pitcut man arm and pull the steering gear assembly out the bottom..
The frame mount is riveted to the frame, top and bottom, the rivets are difficult to get to..
I have '40 Ford steering gears in my '36, installed them in 1955, can't really fathom having a pre '37 Ford with the original steering gears..
You will need to change the pitman arm, I'll have to look up the correct number for use in a '35-36 with later steering gear setup..