Here are some sketches I have worked up. This is the third revision and it gives me the required below grade depth with the best height. I plan to use Arms: 2 x 3 x 3/16", Uprights: 2 x 5 (or 6) x 1/4".
Fixed points: GT (GT14), Cylinders 2.25x19x1.25 (26"/45" eye to eye), two cylinders for lift and one for curl/roll.
Goals: #1; be able to dump over the sides of my car hauler trailer fenders, #2; 4" below grade with 4" of roll, #3; bucket to be as close to the GT as possible.
Other than the limitations listed above nothing is fixed so if you've worked or built one, please give me some insight/advice.