If you make sure the wheels are straight ahead when you torque all of the fasteners, the steering wheel will return to center, provided wheel alignment is correct. Whatever position the wheels are in when you torque the fasteners, is the position the wheels will want to return to. (All steering linkage parts develop a memory when you torque them, including ball joints.)
As for the gear box adjustment, you might want to read this:
http://www.partsmike.com/tech-help/saginaw-adj/