What surveyors call swing ties would work better. Dimensions across corners to break it down into triangles. I'm assuming that the 12-1/2" and 11-3/4" sides are perpendicular and that the 3-3/4" side is parallel to the 11-3/4" side. Dimensions as shown would nail it down.
Thanks for thinking of other 'bolters, John.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.