The dimensions were tough to figure out. Luckily strick had worked through it before.
This bracket will have a 26" setback. Supposedly you need to raise the motor one inch for every 12" of setback. So I made the bracket 23" tall which gives me a 4" gap at the bottom for the hull drain plugs. 25" + 2" (to account for the setback) => 27" = 23" (bracket height) + 4".
The width is 38" b/c that was the width of the fiberglass fabric I used.
13 degrees is what I measured for the angle of the transom.
When I calculated the positive floatation . . . I got somewhere around 400 lbs (depending on the final weight of the bracket.