Move over a little, Mike, I'm moving to Lake Wobegon.

I take it you measure on the surface the 50-15/16" and add the 1/2" shoulders as the housed part of the brace. At least this is what I do on the rare occasion I use your method.

I am actually using 9x timber and house to 1", something about axing the 1/2" housing that seems not justified, 1" seems more worth while.