Chuck the math, assemble the bent with out the brace, check it for true and scribe or trace in a new brace. If the brace is housed you may have to tweak the bevel at the top of the mortice, unless it is an outside brace. If that is too much hassle a block out of special wood embellished in some way so it stands out, and if you need symmetry, make another for the other side. And if you are like me you will make a temporary glut and forget about making the fancy one. Whatever happens don't let it be discouraging, in the end it will be a memorable aspect only you know about and now a few others.