If I'm reading yall correctly, as long as the proportions ar correct, and it looks good it's right, Right?
I just thought that someone (don't matter who) that does this regularly would have templates, being that templates are employed sizes would be the same from unit to unit. Although I'm no expert on Beck, I have noticed that he used similar hardware and designs throughout his career. It just seemed sensible that he would use same dimensions on similar patchbox designs.