Pencon, what I have learned about the way it pulls when in a knife edge is; that if it pulls to the landing gear, it is tail heavy. If it pulls up, it is nose heavy. I am not sure if this is 100 percent true in all cases. Perhaps someone else could chime in on this.
As far as GP or GMP, a Gee Bee is a Gee Bee when it comes to configuration. The differences would probably be in the airfoil or incidence. I can't think of much else unless they stretched it a bit. Now that would be a good idea just to increase the coupling.
All best. bird.