Hey BillyBob58, glad that hammock finally made its way to you. Perhaps you know the story that I made one for AngrySparrow a while back, over a year ago I think, and he has graciously arranged to give you (and some others) a chance for a look-see.
That said, there have been a bunch of GBs made since then and I don't know what dimensions you have. At one time I was using 24" foot ends, but since have increased that trying to give more room in the middle, while still enjoying some of the benefits of the narrower foot.
The length of the ridgeline if you had one would depend on the length of the sides of the suspension triangle, and the length of the hammock. Unlike the Jacks who have a design that is replicated time after time, each of mine is a one-off. The lengths change, I might make the suspension triangles a little longer or a little shorter depending on the weight of the occupant...
You're not going to get a reverse banana in a GB, at least not easily. For that you really need a deeper suspension cut than I've been using. Taking it into the field, increase the tension on the suspension until you see the middle of the body come up a little higher than the ends. Probably you can't get to that point on your stand. That means that when you enter the hammock you'll have more lift in the middle, and that's where the flatness comes from.
Glad you like the hammock!
(alias ProfessorHammock on youtube)