I have put a lot of thought into building a mid-size shovel but it is not possible for me to do the detail work. I can't see well enough to do the detail work and could never gather the info that would be needed. A model with a 30-36" boom is as big as I could do in my shop. But it may be too late for me to start another build-will see. You mentioned a 7'-6" boom-that would be an eye-catcher
The model that don campbell made looks good but it DOESN'T WORK. What a waste! A giant WORKING shovel is what we need. I wish you luck and hope you decide to build this.