The keyway in the steering shaft matches the keyway on the worm gear and will be straight up when you are centered with the steering box like 51 Merc says above. Once you find the center position, you will either have to change the length of your drag link by cutting and welding to keep the stock ends or get an adjustable drag link. Speedway will provide a quality one based on dimensions you provide.
Also take a look at this thread, especially for post #20 on down. When you are checking all your steering components, consider how the heating and bending of the spindle arm affects you.
https://www.fordbarn.com/forum/showt...ndle&showall=1
Glenn