Dan, snap another line up from the bottom tenon line, so it lays on the timber just beyond where the brace locates. I usually use some random even number, no fractions. What ever it is remember it well. This number you will use to locate the brace on the post, in adjustment to the 36" you are using as the brace leg. It wants to just skim the wane, as it is the housing for the brace.

Now for the post, if you are using 9x9 post and housing to 8". Hold 8" on the shoulder line on the tie beam and mark 36", this is the far end of the brace pocket. Use the reference face as the best face and lay the pocket out on the live edge, no snap lines on this face. Assuming it is a best face and not twisted badly.

Does this fit into what you are doing?

The peg will enter the sawn surface on the ref. face, I care not if it exits in the live edge as it exits the far, dark side.