Brad, As far as I am concerned you never lay-out from the inside face the depth of the housing for the brace. I can think of the only time when someone would do that and that is when a inner post has braces that meet on both sides. I personally would create a centerline down the post to lay these out. Even in Mill Rule the reference faces are used as references.

Now back to the curved post. Are you sure about not having to do anything to a brace to make it fit?

Here is a photo of square rule with straight sticks.


Now the problem with the bowed post.




In this situation if you were to use the patterned brace the nosing would be hanging in mid-air and there would be no housing on the post, in short too short. (Example: working 1/2" under nominal)

The only remedy I can see to fix this would be arranging your post with the bow in creating a deeper housing, or picking a different post that is straight damnit, or moving your brace in on your tie 1" towards the post and then work 5" off of your chalkline.